Revert "[Impeller] switch Pipeline to use raw ptr instead of shared ptr for recorded references."

ci/licenses_golden/licenses_flutter

@@ -43017,8 +43017,6 @@ ORIGIN: ../../../flutter/impeller/core/platform.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/core/platform.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/core/range.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/core/range.h + ../../../flutter/LICENSE
-ORIGIN: ../../../flutter/impeller/core/raw_ptr.cc + ../../../flutter/LICENSE
-ORIGIN: ../../../flutter/impeller/core/raw_ptr.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/core/resource_binder.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/core/resource_binder.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/core/runtime_types.cc + ../../../flutter/LICENSE
@@ -45948,8 +45946,6 @@ FILE: ../../../flutter/impeller/core/platform.cc
 FILE: ../../../flutter/impeller/core/platform.h
 FILE: ../../../flutter/impeller/core/range.cc
 FILE: ../../../flutter/impeller/core/range.h
-FILE: ../../../flutter/impeller/core/raw_ptr.cc
-FILE: ../../../flutter/impeller/core/raw_ptr.h
 FILE: ../../../flutter/impeller/core/resource_binder.cc
 FILE: ../../../flutter/impeller/core/resource_binder.h
 FILE: ../../../flutter/impeller/core/runtime_types.cc

impeller/core/BUILD.gn

@@ -23,8 +23,6 @@ impeller_component("core") {
     "platform.h",
     "range.cc",
     "range.h",
-    "raw_ptr.cc",
-    "raw_ptr.h",
     "resource_binder.cc",
     "resource_binder.h",
     "runtime_types.cc",

impeller/entity/contents/color_source_contents.h

@@ -104,7 +104,8 @@ class ColorSourceContents : public Contents {
   using PipelineBuilderMethod = std::shared_ptr<Pipeline<PipelineDescriptor>> (
       impeller::ContentContext::*)(ContentContextOptions) const;
   using PipelineBuilderCallback =
-      std::function<PipelineRef(ContentContextOptions)>;
+      std::function<std::shared_ptr<Pipeline<PipelineDescriptor>>(
+          ContentContextOptions)>;
   using CreateGeometryCallback =
       std::function<GeometryResult(const ContentContext& renderer,
                                    const Entity& entity,

impeller/entity/contents/content_context.cc

@@ -569,7 +569,8 @@ void ContentContext::SetWireframe(bool wireframe) {
   wireframe_ = wireframe;
 }
 
-PipelineRef ContentContext::GetCachedRuntimeEffectPipeline(
+std::shared_ptr<Pipeline<PipelineDescriptor>>
+ContentContext::GetCachedRuntimeEffectPipeline(
     const std::string& unique_entrypoint_name,
     const ContentContextOptions& options,
     const std::function<std::shared_ptr<Pipeline<PipelineDescriptor>>()>&
@@ -579,7 +580,7 @@ PipelineRef ContentContext::GetCachedRuntimeEffectPipeline(
   if (it == runtime_effect_pipelines_.end()) {
     it = runtime_effect_pipelines_.insert(it, {key, create_callback()});
   }
-  return raw_ptr(it->second);
+  return it->second;
 }
 
 void ContentContext::ClearCachedRuntimeEffectPipeline(