Revert of [Prerender] Restore request priorities when swapped in (patchset #1 id:1 of https://codereview.chromium.org/2832473002/ )

Reason for revert:
Caused compile failures on Mac and Windows Beta official desktop continuous waterfall.

https://bugs.chromium.org/p/chromium/issues/detail?id=713223

Original issue's description:
> [Prerender] Restore request priorities when swapped in
>
> Requests from prerendered contents have a IDLE priority, in order not to slow
> down visible pages.
> However, when the prerendered contents become visible, the request priorities
> were not reset back to their correct values, leading to bad prerendering
> performance.
>
> In this CL, the priority management for prerender requests is moved to the
> PrerenderResourceThrottle/PrerendereContents.
> The original priorities are stored in the throttle, and restored when the
> prerender contents swaps in.
> A new public function is added to ResourceDispatcherHost to update a request
> priority, and its implementation reuses the existing code that updates the image
> priorities.
>
> The prerender contents keeps a list of all the network resources that were
> started while the prerender is hidden. If this proves to be too large, pruning
> the list when responses are received should be doable.
>
> BUG=705955
>
> Review-Url: https://codereview.chromium.org/2807163002
> Cr-Commit-Position: refs/heads/master@{#464728}
> (cherry picked from commit d3bc614)
>
> Review-Url: https://codereview.chromium.org/2832473002 .
> Cr-Commit-Position: refs/branch-heads/3071@{#48}
> Cr-Branched-From: a106f0a-refs/heads/master@{#464641}
> Committed: https://chromium.googlesource.com/chromium/src/+/d4b0c9f58ec981f98342cb8438da1a69bb489a06

TBR=droger@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=705955

Review-Url: https://codereview.chromium.org/2833553002
Cr-Commit-Position: refs/branch-heads/3071@{#58}
Cr-Branched-From: a106f0a-refs/heads/master@{#464641}

Author: ojanvafai

chrome/browser/loader/chrome_resource_dispatcher_host_delegate.cc

@@ -443,6 +443,27 @@ void ChromeResourceDispatcherHostDelegate::RequestBeginning(
     safe_browsing_->OnResourceRequest(request);
 
   const ResourceRequestInfo* info = ResourceRequestInfo::ForRequest(request);
+
+// The lowering of request priority causes issues with scheduling, since
+// content::ResourceScheduler uses it to delay and throttle requests. This is
+// disabled only on Android, as the prerenders are not likely to compete with
+// page loads there.
+// See https://crbug.com/652746 for details.
+// TODO(lizeb,droger): Fix the issue on all platforms.
+#if !defined(OS_ANDROID)
+  bool is_prerendering =
+      info->GetVisibilityState() == blink::kWebPageVisibilityStatePrerender;
+  if (is_prerendering) {
+    // Requests with the IGNORE_LIMITS flag set (i.e., sync XHRs)
+    // should remain at MAXIMUM_PRIORITY.
+    if (request->load_flags() & net::LOAD_IGNORE_LIMITS) {
+      DCHECK_EQ(request->priority(), net::MAXIMUM_PRIORITY);
+    } else {
+      request->SetPriority(net::IDLE);
+    }
+  }
+#endif  // OS_ANDROID
+
   ProfileIOData* io_data = ProfileIOData::FromResourceContext(
       resource_context);
 

chrome/browser/prerender/prerender_browsertest.cc

@@ -143,7 +143,7 @@ using content::WebContentsObserver;
 using net::NetworkChangeNotifier;
 using prerender::test_utils::RequestCounter;
 using prerender::test_utils::CreateCountingInterceptorOnIO;
-using prerender::test_utils::CreateHangingFirstRequestInterceptor;
+using prerender::test_utils::CreateHangingFirstRequestInterceptorOnIO;
 using prerender::test_utils::CreateMockInterceptorOnIO;
 using prerender::test_utils::TestPrerender;
 using prerender::test_utils::TestPrerenderContents;
@@ -166,8 +166,6 @@ namespace prerender {
 
 namespace {
 
-const char kPrefetchJpeg[] = "/prerender/image.jpeg";
-
 class FaviconUpdateWatcher : public favicon::FaviconDriverObserver {
  public:
   explicit FaviconUpdateWatcher(content::WebContents* web_contents)
@@ -541,17 +539,6 @@ page_load_metrics::PageLoadExtraInfo GenericPageLoadExtraInfo(
       dest_url, false /* started_in_foreground */);
 }
 
-// Helper function, to allow passing a UI closure to
-// CreateHangingFirstRequestInterceptor() instead of a IO callback.
-base::Callback<void(net::URLRequest*)> GetIOCallbackFromUIClosure(
-    base::Closure ui_closure) {
-  auto lambda = [](base::Closure closure, net::URLRequest*) {
-    content::BrowserThread::PostTask(content::BrowserThread::UI, FROM_HERE,
-                                     closure);
-  };
-  return base::Bind(lambda, ui_closure);
-}
-
 }  // namespace
 
 class PrerenderBrowserTest : public test_utils::PrerenderInProcessBrowserTest {
@@ -1315,9 +1302,10 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, MAYBE_PrerenderNoCommitNoSwap) {
   base::FilePath file(GetTestPath("prerender_page.html"));
 
   base::RunLoop prerender_start_loop;
-  CreateHangingFirstRequestInterceptor(
-      kNoCommitUrl, file,
-      GetIOCallbackFromUIClosure(prerender_start_loop.QuitClosure()));
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&CreateHangingFirstRequestInterceptorOnIO, kNoCommitUrl, file,
+                 prerender_start_loop.QuitClosure()));
   DisableJavascriptCalls();
   PrerenderTestURL(kNoCommitUrl,
                    FINAL_STATUS_NAVIGATION_UNCOMMITTED,
@@ -1342,9 +1330,10 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, MAYBE_PrerenderNoCommitNoSwap2) {
   base::FilePath file(GetTestPath("prerender_page.html"));
 
   base::RunLoop prerender_start_loop;
-  CreateHangingFirstRequestInterceptor(
-      kNoCommitUrl, file,
-      GetIOCallbackFromUIClosure(prerender_start_loop.QuitClosure()));
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&CreateHangingFirstRequestInterceptorOnIO, kNoCommitUrl, file,
+                 prerender_start_loop.QuitClosure()));
   DisableJavascriptCalls();
   PrerenderTestURL(CreateClientRedirect(kNoCommitUrl.spec()),
                    FINAL_STATUS_APP_TERMINATING, 1);
@@ -2120,7 +2109,7 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderImagePng) {
 // Checks that prerendering a JPG works correctly.
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderImageJpeg) {
   DisableJavascriptCalls();
-  PrerenderTestURL(kPrefetchJpeg, FINAL_STATUS_USED, 1);
+  PrerenderTestURL("/prerender/image.jpeg", FINAL_STATUS_USED, 1);
   NavigateToDestURL();
 }
 
@@ -2192,7 +2181,7 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderSSLErrorSubresource) {
   https_server.SetSSLConfig(net::EmbeddedTestServer::CERT_MISMATCHED_NAME);
   https_server.ServeFilesFromSourceDirectory("chrome/test/data");
   ASSERT_TRUE(https_server.Start());
-  GURL https_url = https_server.GetURL(kPrefetchJpeg);
+  GURL https_url = https_server.GetURL("/prerender/image.jpeg");
   base::StringPairs replacement_text;
   replacement_text.push_back(
       std::make_pair("REPLACE_WITH_IMAGE_URL", https_url.spec()));
@@ -2304,7 +2293,7 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest,
   https_server.SetSSLConfig(net::EmbeddedTestServer::CERT_OK, ssl_config);
   https_server.ServeFilesFromSourceDirectory("chrome/test/data");
   ASSERT_TRUE(https_server.Start());
-  GURL https_url = https_server.GetURL(kPrefetchJpeg);
+  GURL https_url = https_server.GetURL("/prerender/image.jpeg");
   base::StringPairs replacement_text;
   replacement_text.push_back(
       std::make_pair("REPLACE_WITH_IMAGE_URL", https_url.spec()));
@@ -2378,7 +2367,7 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest,
 
 // Ensures that we do not prerender pages which have a malware subresource.
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderSafeBrowsingSubresource) {
-  GURL image_url = embedded_test_server()->GetURL(kPrefetchJpeg);
+  GURL image_url = embedded_test_server()->GetURL("/prerender/image.jpeg");
   GetFakeSafeBrowsingDatabaseManager()->SetThreatTypeForUrl(
       image_url, safe_browsing::SB_THREAT_TYPE_URL_MALWARE);
   base::StringPairs replacement_text;
@@ -2502,8 +2491,11 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderHangingUnload) {
   const GURL hang_url("http://unload-url.test");
   base::FilePath empty_file = ui_test_utils::GetTestFilePath(
       base::FilePath(), base::FilePath(FILE_PATH_LITERAL("empty.html")));
-  CreateHangingFirstRequestInterceptor(
-      hang_url, empty_file, base::Callback<void(net::URLRequest*)>());
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&CreateHangingFirstRequestInterceptorOnIO,
+                 hang_url, empty_file,
+                 base::Closure()));
 
   set_loader_path("/prerender/prerender_loader_with_unload.html");
   PrerenderTestURL("/prerender/prerender_page.html", FINAL_STATUS_USED, 1);
@@ -3299,122 +3291,6 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, AutosigninInPrerenderer) {
   EXPECT_EQ(0, done_counter.count());
 }
 
-// Checks that the requests from a prerender are IDLE priority before the swap
-// (except on Android), but normal priority after the swap.
-IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, ResourcePriority) {
-  GURL before_swap_url = embedded_test_server()->GetURL(kPrefetchJpeg);
-  GURL after_swap_url = embedded_test_server()->GetURL("/prerender/image.png");
-  GURL main_page_url =
-      GetURLWithReplacement("/prerender/prerender_with_image.html",
-                            "REPLACE_WITH_IMAGE_URL", kPrefetchJpeg);
-
-  // Setup request interceptors for subresources.
-  auto get_priority_lambda = [](net::RequestPriority* out_priority,
-                                net::URLRequest* request) {
-    *out_priority = request->priority();
-  };
-  RequestCounter before_swap_counter;
-  net::RequestPriority before_swap_priority = net::THROTTLED;
-  InterceptRequestAndCount(
-      before_swap_url, &before_swap_counter,
-      base::Bind(get_priority_lambda, base::Unretained(&before_swap_priority)));
-  RequestCounter after_swap_counter;
-  net::RequestPriority after_swap_priority = net::THROTTLED;
-  InterceptRequestAndCount(
-      after_swap_url, &after_swap_counter,
-      base::Bind(get_priority_lambda, base::Unretained(&after_swap_priority)));
-
-  // Start the prerender.
-  PrerenderTestURL(main_page_url, FINAL_STATUS_USED, 1);
-
-  // Check priority before swap.
-  before_swap_counter.WaitForCount(1);
-#if defined(OS_ANDROID)
-  EXPECT_GT(before_swap_priority, net::IDLE);
-#else
-  EXPECT_EQ(net::IDLE, before_swap_priority);
-#endif
-
-  // Swap.
-  NavigateToDestURL();
-
-  // Check priority after swap.
-  GetActiveWebContents()->GetMainFrame()->ExecuteJavaScriptForTests(
-      base::ASCIIToUTF16(
-          "var img=new Image(); img.src='/prerender/image.png'"));
-  after_swap_counter.WaitForCount(1);
-  EXPECT_NE(net::IDLE, after_swap_priority);
-}
-
-// Checks that a request started before the swap gets its original priority back
-// after the swap.
-IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, ResourcePriorityOverlappingSwap) {
-  GURL image_url = embedded_test_server()->GetURL(kPrefetchJpeg);
-  GURL main_page_url =
-      GetURLWithReplacement("/prerender/prerender_with_image.html",
-                            "REPLACE_WITH_IMAGE_URL", kPrefetchJpeg);
-
-  // Setup request interceptors for subresources.
-  net::URLRequest* url_request = nullptr;
-  net::RequestPriority priority = net::THROTTLED;
-  base::RunLoop wait_loop;
-  auto io_lambda = [](net::URLRequest** out_request,
-                      net::RequestPriority* out_priority, base::Closure closure,
-                      net::URLRequest* request) {
-    if (out_request)
-      *out_request = request;
-    content::BrowserThread::PostTask(
-        content::BrowserThread::UI, FROM_HERE,
-        base::Bind(
-            [](net::RequestPriority priority,
-               net::RequestPriority* out_priority, base::Closure closure) {
-              *out_priority = priority;
-              closure.Run();
-            },
-            request->priority(), base::Unretained(out_priority), closure));
-  };
-
-  CreateHangingFirstRequestInterceptor(
-      image_url, base::FilePath(),
-      base::Bind(io_lambda, base::Unretained(&url_request),
-                 base::Unretained(&priority), wait_loop.QuitClosure()));
-
-  // The prerender will hang on the image resource, can't run the usual checks.
-  DisableLoadEventCheck();
-  DisableJavascriptCalls();
-  // Start the prerender.
-  PrerenderTestURL(main_page_url, FINAL_STATUS_USED, 0);
-
-// Check priority before swap.
-#if defined(OS_ANDROID)
-  if (priority <= net::IDLE)
-    wait_loop.Run();
-  EXPECT_GT(priority, net::IDLE);
-#else
-  if (priority != net::IDLE)
-    wait_loop.Run();
-  EXPECT_EQ(net::IDLE, priority);
-#endif
-
-  // Swap. Cannot use NavigateToDestURL, because it waits for the load to
-  // complete, but the resource is still hung.
-  current_browser()->OpenURL(content::OpenURLParams(
-      dest_url(), Referrer(), WindowOpenDisposition::CURRENT_TAB,
-      ui::PAGE_TRANSITION_TYPED, false));
-
-  // Check priority after swap. The test may timeout in case of failure.
-  priority = net::THROTTLED;
-  do {
-    base::RunLoop loop;
-    content::BrowserThread::PostTask(
-        content::BrowserThread::IO, FROM_HERE,
-        base::Bind(io_lambda, nullptr, base::Unretained(&priority),
-                   loop.QuitClosure(), base::Unretained(url_request)));
-    loop.Run();
-  } while (priority <= net::IDLE);
-  EXPECT_GT(priority, net::IDLE);
-}
-
 IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, FirstContentfulPaintTimingSimple) {
   GetPrerenderManager()->DisablePageLoadMetricsObserverForTesting();
   base::SimpleTestTickClock* clock = OverridePrerenderManagerTimeTicks();
@@ -3447,9 +3323,10 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, FirstContentfulPaintTimingReuse) {
 
   GURL url = embedded_test_server()->GetURL("/prerender/prerender_page.html");
   base::RunLoop hanging_request_waiter;
-  CreateHangingFirstRequestInterceptor(
-      url, GetTestPath("prerender_page.html"),
-      GetIOCallbackFromUIClosure(hanging_request_waiter.QuitClosure()));
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+                          base::Bind(&CreateHangingFirstRequestInterceptorOnIO,
+                                     url, GetTestPath("prerender_page.html"),
+                                     hanging_request_waiter.QuitClosure()));
   // As this load will be canceled, it is not waited for, and hence no
   // javascript is executed.
   DisableJavascriptCalls();
@@ -3534,9 +3411,10 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest,
       base::FilePath(FILE_PATH_LITERAL("prerender/prerender_page.html")));
 
   base::RunLoop prerender_start_loop;
-  CreateHangingFirstRequestInterceptor(
-      url, url_file,
-      GetIOCallbackFromUIClosure(prerender_start_loop.QuitClosure()));
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&CreateHangingFirstRequestInterceptorOnIO, url, url_file,
+                 prerender_start_loop.QuitClosure()));
   // As this load is uncommitted, it is not waited for, and hence no
   // javascript is executed.
   DisableJavascriptCalls();
@@ -3653,9 +3531,10 @@ IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest,
       base::FilePath(FILE_PATH_LITERAL("prerender/prerender_page.html")));
 
   base::RunLoop prerender_start_loop;
-  CreateHangingFirstRequestInterceptor(
-      url, url_file,
-      GetIOCallbackFromUIClosure(prerender_start_loop.QuitClosure()));
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&CreateHangingFirstRequestInterceptorOnIO, url, url_file,
+                 prerender_start_loop.QuitClosure()));
   // As this load is uncommitted, it is not waited for, and hence no
   // javascript is executed.
   DisableJavascriptCalls();

chrome/browser/prerender/prerender_contents.cc

@@ -70,12 +70,7 @@ const char* const kValidHttpMethodsForPrerendering[] = {
 };
 
 void ResumeThrottles(
-    std::vector<base::WeakPtr<PrerenderResourceThrottle>> throttles,
-    std::vector<base::WeakPtr<PrerenderResourceThrottle>> idle_resources) {
-  for (auto resource : idle_resources) {
-    if (resource)
-      resource->ResetResourcePriority();
-  }
+    std::vector<base::WeakPtr<PrerenderResourceThrottle> > throttles) {
   for (size_t i = 0; i < throttles.size(); i++) {
     if (throttles[i])
       throttles[i]->ResumeHandler();
@@ -762,10 +757,10 @@ void PrerenderContents::PrepareForUse() {
   NotifyPrerenderStop();
 
   BrowserThread::PostTask(
-      BrowserThread::IO, FROM_HERE,
-      base::Bind(&ResumeThrottles, resource_throttles_, idle_resources_));
+      BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&ResumeThrottles, resource_throttles_));
   resource_throttles_.clear();
-  idle_resources_.clear();
 }
 
 void PrerenderContents::CancelPrerenderForPrinting() {
@@ -783,11 +778,6 @@ void PrerenderContents::AddResourceThrottle(
   resource_throttles_.push_back(throttle);
 }
 
-void PrerenderContents::AddIdleResource(
-    const base::WeakPtr<PrerenderResourceThrottle>& throttle) {
-  idle_resources_.push_back(throttle);
-}
-
 void PrerenderContents::AddNetworkBytes(int64_t bytes) {
   network_bytes_ += bytes;
   for (Observer& observer : observer_list_)

chrome/browser/prerender/prerender_contents.h

@@ -235,12 +235,6 @@ class PrerenderContents : public content::NotificationObserver,
   void AddResourceThrottle(
       const base::WeakPtr<PrerenderResourceThrottle>& throttle);
 
-  // Called when a PrerenderResourceThrottle changes a resource priority to
-  // net::IDLE. The resources are reset back to their original priorities when
-  // the prerender contents is swapped in.
-  void AddIdleResource(
-      const base::WeakPtr<PrerenderResourceThrottle>& throttle);
-
   // Increments the number of bytes fetched over the network for this prerender.
   void AddNetworkBytes(int64_t bytes);
 
@@ -378,8 +372,6 @@ class PrerenderContents : public content::NotificationObserver,
   // Resources that are throttled, pending a prerender use. Can only access a
   // throttle on the IO thread.
   std::vector<base::WeakPtr<PrerenderResourceThrottle> > resource_throttles_;
-  // Resources for which the priority was lowered to net::IDLE.
-  std::vector<base::WeakPtr<PrerenderResourceThrottle>> idle_resources_;
 
   // A running tally of the number of bytes this prerender has caused to be
   // transferred over the network for resources.  Updated with AddNetworkBytes.

chrome/browser/prerender/prerender_nostate_prefetch_browsertest.cc

@@ -284,8 +284,10 @@ IN_PROC_BROWSER_TEST_F(NoStatePrefetchBrowserTest, PrefetchSimultaneous) {
   base::FilePath first_path = ui_test_utils::GetTestFilePath(
       base::FilePath(), base::FilePath().AppendASCII(kPrefetchPage));
 
-  test_utils::CreateHangingFirstRequestInterceptor(
-      first_url, first_path, base::Callback<void(net::URLRequest*)>());
+  content::BrowserThread::PostTask(
+      content::BrowserThread::IO, FROM_HERE,
+      base::Bind(&test_utils::CreateHangingFirstRequestInterceptorOnIO,
+                 first_url, first_path, base::Closure()));
 
   // Start the first prefetch directly instead of via PrefetchFromFile for the
   // first prefetch to avoid the wait on prerender stop.