Make OffscreenCanvas animation in sync with its placeholder canvas's parent frame rate

content/browser/renderer_host/offscreen_canvas_surface_manager.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/lazy_instance.h"
 #include "cc/surfaces/surface_manager.h"
 #include "content/browser/compositor/surface_utils.h"
 #include "content/browser/renderer_host/offscreen_canvas_surface_manager.h"
 
 namespace content {
 
 namespace {
 base::LazyInstance<OffscreenCanvasSurfaceManager>::Leaky g_manager =
     LAZY_INSTANCE_INITIALIZER;
 }
 
 OffscreenCanvasSurfaceManager::OffscreenCanvasSurfaceManager() {
   GetSurfaceManager()->AddObserver(this);
 }
 
 OffscreenCanvasSurfaceManager::~OffscreenCanvasSurfaceManager() {
   registered_surface_instances_.clear();
   GetSurfaceManager()->RemoveObserver(this);
 }
 
 OffscreenCanvasSurfaceManager* OffscreenCanvasSurfaceManager::GetInstance() {
   return g_manager.Pointer();
 }
 
+void OffscreenCanvasSurfaceManager::RegisterFrameSinkToItsParent(

[Fady Samuel, 2017/01/19 04:05:43]

nit: RegisterFrameSinkToParent?

[xlai (Olivia), 2017/01/19 16:43:56]

Done.

+    cc::FrameSinkId child_frame_sink_id) {

[Fady Samuel, 2017/01/19 04:05:43]

nit: const cc::FrameSinkId&

[xlai (Olivia), 2017/01/19 16:43:56]

Done.

+  auto surface_iter = registered_surface_instances_.find(child_frame_sink_id);
+  if (surface_iter == registered_surface_instances_.end())
+    return;
+  OffscreenCanvasSurfaceImpl* surfaceImpl = surface_iter->second;
+  if (surfaceImpl->parent_frame_sink_id().is_valid()) {
+    GetSurfaceManager()->RegisterFrameSinkHierarchy(
+        surfaceImpl->parent_frame_sink_id(), child_frame_sink_id);
+  }
+}
+
+void OffscreenCanvasSurfaceManager::UnregisterFrameSinkFromItsParent(

[Fady Samuel, 2017/01/19 04:05:43]

nit: UnregisterFrameSinkFromParent?

[xlai (Olivia), 2017/01/19 16:43:56]

Done.

+    cc::FrameSinkId child_frame_sink_id) {

[Fady Samuel, 2017/01/19 04:05:43]

const cc::FrameSinkId&

[xlai (Olivia), 2017/01/19 16:43:56]

Done.

+  auto surface_iter = registered_surface_instances_.find(child_frame_sink_id);
+  if (surface_iter == registered_surface_instances_.end())
+    return;
+  OffscreenCanvasSurfaceImpl* surfaceImpl = surface_iter->second;
+  if (surfaceImpl->parent_frame_sink_id().is_valid()) {
+    GetSurfaceManager()->UnregisterFrameSinkHierarchy(
+        surfaceImpl->parent_frame_sink_id(), child_frame_sink_id);
+  }
+}
+
 void OffscreenCanvasSurfaceManager::OnSurfaceCreated(
     const cc::SurfaceInfo& surface_info) {
   auto surface_iter =
       registered_surface_instances_.find(surface_info.id().frame_sink_id());
   if (surface_iter == registered_surface_instances_.end())
     return;
   OffscreenCanvasSurfaceImpl* surfaceImpl = surface_iter->second;
   surfaceImpl->OnSurfaceCreated(surface_info);
 }
 
 void OffscreenCanvasSurfaceManager::RegisterOffscreenCanvasSurfaceInstance(
     cc::FrameSinkId frame_sink_id,

[Fady Samuel, 2017/01/19 04:05:43]

nit: const cc::FrameSinkId&

[xlai (Olivia), 2017/01/19 16:43:56]

Done.

     OffscreenCanvasSurfaceImpl* surface_instance) {
   DCHECK(surface_instance);
   DCHECK_EQ(registered_surface_instances_.count(frame_sink_id), 0u);
   registered_surface_instances_[frame_sink_id] = surface_instance;
 }
 
 void OffscreenCanvasSurfaceManager::UnregisterOffscreenCanvasSurfaceInstance(
     cc::FrameSinkId frame_sink_id) {

[Fady Samuel, 2017/01/19 04:05:43]

nit: const cc::FrameSinkId&

[xlai (Olivia), 2017/01/19 16:43:56]

Done.

   DCHECK_EQ(registered_surface_instances_.count(frame_sink_id), 1u);
   registered_surface_instances_.erase(frame_sink_id);
 }
 
 OffscreenCanvasSurfaceImpl* OffscreenCanvasSurfaceManager::GetSurfaceInstance(
     cc::FrameSinkId frame_sink_id) {

[Fady Samuel, 2017/01/19 04:05:43]

nit: const cc::FrameSinkId&

[xlai (Olivia), 2017/01/19 16:43:56]

Done.

   auto search = registered_surface_instances_.find(frame_sink_id);
   if (search != registered_surface_instances_.end()) {
     return search->second;
   }
   return nullptr;
 }
 
 }  // namespace content