Fix an issue where touch events were dispatched to the incorrect webview

Was caused by touchscreen_gesture_target_queue_ + prevent default.  The
webview target was calculated on TouchStart and pushed to the the queue.
It was removed on its corresponding GestureTapDown.  However, if the
TouchStart had default behavior prevented, no GestureTapDown would ever
occur, and the queue would forever have an extra element.

Fixed by converting touchscreen_gesture_target_queue_ to a map with
unique_touch_event_id as keys and gesture target data as values.

Also updates AUTHORS file.

TBR=nathan.fairhurst@nike.com

(cherry picked from commit 09a2f88)

Bug: 736623, 739831
Change-Id: If3bf844e2bcfb9a1ca6d6a56cdc7575e0767e6b6
Reviewed-on: https://chromium-review.googlesource.com/547669
Commit-Queue: James MacLean <wjmaclean@chromium.org>
Reviewed-by: Charlie Reis <creis@chromium.org>
Reviewed-by: Ken Buchanan <kenrb@chromium.org>
Reviewed-by: James MacLean <wjmaclean@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#488759}
Reviewed-on: https://chromium-review.googlesource.com/586747
Cr-Commit-Position: refs/branch-heads/3163@{#54}
Cr-Branched-From: ff259ba-refs/heads/master@{#488528}

Author: W. James MacLean

AUTHORS

@@ -863,6 +863,7 @@ Endless Mobile, Inc. <*@endlessm.com>
 Google Inc. <*@google.com>
 Hewlett-Packard Development Company, L.P. <*@hp.com>
 Igalia S.L. <*@igalia.com>
+NIKE, Inc. <*@nike.com>
 NVIDIA Corporation <*@nvidia.com>
 Neverware Inc. <*@neverware.com>
 Opera Software ASA <*@opera.com>

content/browser/renderer_host/render_widget_host_input_event_router.cc

@@ -57,12 +57,12 @@ void RenderWidgetHostInputEventRouter::OnRenderWidgetHostViewBaseDestroyed(
     active_touches_ = 0;
   }
 
-  // If the target that's being destroyed is in the gesture target queue, we
+  // If the target that's being destroyed is in the gesture target map, we
   // replace it with nullptr so that we maintain the 1:1 correspondence between
-  // queue entries and the touch sequences that underly them.
-  for (size_t i = 0; i < touchscreen_gesture_target_queue_.size(); ++i) {
-    if (touchscreen_gesture_target_queue_[i].target == view)
-      touchscreen_gesture_target_queue_[i].target = nullptr;
+  // map entries and the touch sequences that underly them.
+  for (auto it : touchscreen_gesture_target_map_) {
+    if (it.second.target == view)
+      it.second.target = nullptr;
   }
 
   if (view == mouse_capture_target_.target)
@@ -390,6 +390,15 @@ unsigned CountChangedTouchPoints(const blink::WebTouchEvent& event) {
 
 }  // namespace
 
+// Any time a touch start event is handled/consumed/default prevented it is
+// removed from the gesture map, because it will never create a gesture.
+void RenderWidgetHostInputEventRouter::OnHandledTouchStartOrFirstTouchMove(
+    uint32_t unique_touch_event_id) {
+  // unique_touch_event_id of 0 implies a gesture not created by a touch.
+  DCHECK_NE(unique_touch_event_id, 0U);
+  touchscreen_gesture_target_map_.erase(unique_touch_event_id);
+}
+
 void RenderWidgetHostInputEventRouter::RouteTouchEvent(
     RenderWidgetHostViewBase* root_view,
     blink::WebTouchEvent* event,
@@ -413,7 +422,11 @@ void RenderWidgetHostInputEventRouter::RouteTouchEvent(
         // might be to always transform each point to the |touch_target_.target|
         // for the duration of the sequence.
         touch_target_.delta = transformed_point - original_point;
-        touchscreen_gesture_target_queue_.push_back(touch_target_);
+        DCHECK(touchscreen_gesture_target_map_.find(
+                   event->unique_touch_event_id) ==
+               touchscreen_gesture_target_map_.end());
+        touchscreen_gesture_target_map_[event->unique_touch_event_id] =
+            touch_target_;
 
         if (!touch_target_.target)
           return;
@@ -835,23 +848,45 @@ void RenderWidgetHostInputEventRouter::RouteTouchscreenGestureEvent(
     return;
   }
 
+  auto gesture_target_it =
+      touchscreen_gesture_target_map_.find(event->unique_touch_event_id);
+  bool no_matching_id =
+      gesture_target_it == touchscreen_gesture_target_map_.end();
+
+  // We use GestureTapDown to detect the start of a gesture sequence since
+  // there is no WebGestureEvent equivalent for ET_GESTURE_BEGIN. Note that
+  // this means the GestureFlingCancel that always comes between
+  // ET_GESTURE_BEGIN and GestureTapDown is sent to the previous target, in
+  // case it is still in a fling.
+  bool is_gesture_start =
+      event->GetType() == blink::WebInputEvent::kGestureTapDown;
+
   // On Android it is possible for touchscreen gesture events to arrive that
   // are not associated with touch events, because non-synthetic events can be
-  // created by ContentView. In that case the target queue will be empty.
-  if (touchscreen_gesture_target_queue_.empty()) {
+  // created by ContentView.
+  // These gesture events should always have a unique_touch_event_id of 0.
+  bool no_gesture_target =
+      event->unique_touch_event_id != 0 && no_matching_id && is_gesture_start;
+
+  if (no_gesture_target) {
+    UMA_HISTOGRAM_BOOLEAN("Event.FrameEventRouting.NoGestureTarget",
+                          no_gesture_target);
+    NOTREACHED() << "Gesture sequence start detected with no target available.";
+    // It is still safe to continue; we will recalculate the target.
+  }
+
+  // If this is a non-touch gesture or there was an no_matching_id error on
+  // gesture start, then the target must be recalculated.
+  if (event->unique_touch_event_id == 0 ||
+      (no_matching_id && is_gesture_start)) {
     gfx::Point transformed_point;
     gfx::Point original_point(event->x, event->y);
     touchscreen_gesture_target_.target =
         FindEventTarget(root_view, original_point, &transformed_point);
     touchscreen_gesture_target_.delta = transformed_point - original_point;
-  } else if (event->GetType() == blink::WebInputEvent::kGestureTapDown) {
-    // We use GestureTapDown to detect the start of a gesture sequence since
-    // there is no WebGestureEvent equivalent for ET_GESTURE_BEGIN. Note that
-    // this means the GestureFlingCancel that always comes between
-    // ET_GESTURE_BEGIN and GestureTapDown is sent to the previous target, in
-    // case it is still in a fling.
-    touchscreen_gesture_target_ = touchscreen_gesture_target_queue_.front();
-    touchscreen_gesture_target_queue_.pop_front();
+  } else if (is_gesture_start) {
+    touchscreen_gesture_target_ = gesture_target_it->second;
+    touchscreen_gesture_target_map_.erase(gesture_target_it);
 
     // Abort any scroll bubbling in progress to avoid double entry.
     if (touchscreen_gesture_target_.target &&

content/browser/renderer_host/render_widget_host_input_event_router.h

@@ -7,7 +7,7 @@
 
 #include <stdint.h>
 
-#include <deque>
+#include <map>
 #include <unordered_map>
 #include <vector>
 
@@ -67,6 +67,7 @@ class CONTENT_EXPORT RenderWidgetHostInputEventRouter
   void RouteGestureEvent(RenderWidgetHostViewBase* root_view,
                          blink::WebGestureEvent* event,
                          const ui::LatencyInfo& latency);
+  void OnHandledTouchStartOrFirstTouchMove(uint32_t unique_touch_event_id);
   void RouteTouchEvent(RenderWidgetHostViewBase* root_view,
                        blink::WebTouchEvent *event,
                        const ui::LatencyInfo& latency);
@@ -125,7 +126,7 @@ class CONTENT_EXPORT RenderWidgetHostInputEventRouter
 
     TargetData() : target(nullptr) {}
   };
-  using TargetQueue = std::deque<TargetData>;
+  using TargetMap = std::map<uint32_t, TargetData>;
 
   void ClearAllObserverRegistrations();
 
@@ -158,7 +159,7 @@ class CONTENT_EXPORT RenderWidgetHostInputEventRouter
                             const blink::WebGestureEvent& event);
 
   FrameSinkIdOwnerMap owner_map_;
-  TargetQueue touchscreen_gesture_target_queue_;
+  TargetMap touchscreen_gesture_target_map_;
   TargetData touch_target_;
   TargetData touchscreen_gesture_target_;
   TargetData touchpad_gesture_target_;
@@ -185,7 +186,9 @@ class CONTENT_EXPORT RenderWidgetHostInputEventRouter
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostInputEventRouter);
   FRIEND_TEST_ALL_PREFIXES(SitePerProcessBrowserTest,
-                           InputEventRouterGestureTargetQueueTest);
+                           InputEventRouterGestureTargetMapTest);
+  FRIEND_TEST_ALL_PREFIXES(SitePerProcessBrowserTest,
+                           InputEventRouterGesturePreventDefaultTargetMapTest);
   FRIEND_TEST_ALL_PREFIXES(SitePerProcessBrowserTest,
                            InputEventRouterTouchpadGestureTargetTest);
 };

content/browser/renderer_host/render_widget_host_view_android.cc

@@ -1748,6 +1748,13 @@ void RenderWidgetHostViewAndroid::ProcessAckedTouchEvent(
   gesture_provider_.OnTouchEventAck(
       touch.event.unique_touch_event_id, event_consumed,
       InputEventAckStateIsSetNonBlocking(ack_result));
+  if (touch.event.touch_start_or_first_touch_move && event_consumed &&
+      host_->delegate() && host_->delegate()->GetInputEventRouter()) {
+    host_->delegate()
+        ->GetInputEventRouter()
+        ->OnHandledTouchStartOrFirstTouchMove(
+            touch.event.unique_touch_event_id);
+  }
 }
 
 void RenderWidgetHostViewAndroid::GestureEventAck(

content/browser/renderer_host/render_widget_host_view_aura.cc

@@ -1071,6 +1071,14 @@ void RenderWidgetHostViewAura::ProcessAckedTouchEvent(
       host->dispatcher()->ProcessedTouchEvent(
           touch.event.unique_touch_event_id, window_, result,
           InputEventAckStateIsSetNonBlocking(ack_result));
+      if (touch.event.touch_start_or_first_touch_move &&
+          result == ui::ER_HANDLED && host_->delegate() &&
+          host_->delegate()->GetInputEventRouter()) {
+        host_->delegate()
+            ->GetInputEventRouter()
+            ->OnHandledTouchStartOrFirstTouchMove(
+                touch.event.unique_touch_event_id);
+      }
       sent_ack = true;
     }
   }