content: fixs sending OnRootScrollOffsetChanged too often

OnRootScrollOffsetChanged should only be sent if all root scroll
offsets have been requested and only on android.

BUG=1100552
TEST=none

Change-Id: Ibc53cf127df0107e5ac69f9378601c9d25d357e1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2283056Reviewed-by: Bo <boliu@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#785790}

content/browser/renderer_host/render_frame_metadata_provider_impl.cc

@@ -127,10 +127,12 @@ void RenderFrameMetadataProviderImpl::OnFrameSubmissionForTesting(
                                   weak_factory_.GetWeakPtr()));
 }
 
+#if defined(OS_ANDROID)
 void RenderFrameMetadataProviderImpl::OnRootScrollOffsetChanged(
     const gfx::Vector2dF& root_scroll_offset) {
   for (Observer& observer : observers_)
     observer.OnRootScrollOffsetChanged(root_scroll_offset);
 }
+#endif
 
 }  // namespace content

content/browser/renderer_host/render_frame_metadata_provider_impl.h

@@ -76,8 +76,10 @@ class CONTENT_EXPORT RenderFrameMetadataProviderImpl
       uint32_t frame_token,
       const cc::RenderFrameMetadata& metadata) override;
   void OnFrameSubmissionForTesting(uint32_t frame_token) override;
+#if defined(OS_ANDROID)
   void OnRootScrollOffsetChanged(
       const gfx::Vector2dF& root_scroll_offset) override;
+#endif
 
   base::ObserverList<Observer>::Unchecked observers_;
 

content/common/render_frame_metadata.mojom

@@ -135,5 +135,6 @@ interface RenderFrameMetadataObserverClient {
 
   // Only called if ReportAllRootScrolls(true) has been called. See
   // ReportAllRootScrolls() for details.
+  [EnableIf=is_android]
   OnRootScrollOffsetChanged(gfx.mojom.Vector2dF root_scroll_offset);
 };

content/public/browser/render_frame_metadata_provider.h

@@ -6,6 +6,7 @@
 #define CONTENT_PUBLIC_BROWSER_RENDER_FRAME_METADATA_PROVIDER_H_
 
 #include "base/macros.h"
+#include "build/build_config.h"
 #include "cc/trees/render_frame_metadata.h"
 #include "content/common/content_export.h"
 
@@ -40,8 +41,10 @@ class CONTENT_EXPORT RenderFrameMetadataProvider {
     // to pass in Viz.
     virtual void OnLocalSurfaceIdChanged(
         const cc::RenderFrameMetadata& metadata) = 0;
+#if defined(OS_ANDROID)
     virtual void OnRootScrollOffsetChanged(
         const gfx::Vector2dF& root_scroll_offset) {}
+#endif
   };
 
   RenderFrameMetadataProvider() = default;

content/renderer/render_frame_metadata_observer_impl.cc

@@ -58,11 +58,14 @@ void RenderFrameMetadataObserverImpl::OnRenderFrameSubmission(
     send_metadata |= force_send;
   }
 
+#if defined(OS_ANDROID)
   const bool send_root_scroll_offset_changed =
-      !send_metadata && last_render_frame_metadata_ &&
+      report_all_root_scrolls_enabled_ && !send_metadata &&
+      render_frame_metadata_observer_client_ && last_render_frame_metadata_ &&
       last_render_frame_metadata_->root_scroll_offset !=
           render_frame_metadata.root_scroll_offset &&
       render_frame_metadata.root_scroll_offset.has_value();
+#endif
 
   // Always cache the full metadata, so that it can correctly be sent upon
   // ReportAllFrameSubmissionsForTesting or on android, which notifies on any
@@ -103,11 +106,14 @@ void RenderFrameMetadataObserverImpl::OnRenderFrameSubmission(
             ? metadata_copy.local_surface_id_allocation->local_surface_id()
                   .ToString()
             : "null");
-  } else if (render_frame_metadata_observer_client_ &&
-             send_root_scroll_offset_changed) {
+  }
+
+#if defined(OS_ANDROID)
+  if (send_root_scroll_offset_changed) {
     render_frame_metadata_observer_client_->OnRootScrollOffsetChanged(
         *render_frame_metadata.root_scroll_offset);
   }
+#endif
 
   // Always cache the initial frame token, so that if a test connects later on
   // it can be notified of the initial state.

content/renderer/render_frame_metadata_observer_impl_unittest.cc

@@ -42,7 +42,9 @@ class MockRenderFrameMetadataObserverClient
                void(uint32_t frame_token,
                     const cc::RenderFrameMetadata& metadata));
   MOCK_METHOD1(OnFrameSubmissionForTesting, void(uint32_t frame_token));
+#if defined(OS_ANDROID)
   MOCK_METHOD1(OnRootScrollOffsetChanged, void(const gfx::Vector2dF& offset));
+#endif
 
  private:
   mojo::Receiver<mojom::RenderFrameMetadataObserverClient>