Android: Throttle BeginFrame messages sent from the browser.

content/browser/renderer_host/render_widget_host_view_android.cc

 // Copyright (c) 2012 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 "content/browser/renderer_host/render_widget_host_view_android.h"
 
 #include <android/bitmap.h>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 63 matching lines @@
 
 RenderWidgetHostViewAndroid::RenderWidgetHostViewAndroid(
     RenderWidgetHostImpl* widget_host,
     ContentViewCoreImpl* content_view_core)
     : host_(widget_host),
       are_layers_attached_(true),
       content_view_core_(NULL),
       ime_adapter_android_(this),
       cached_background_color_(SK_ColorWHITE),
       texture_id_in_layer_(0),
-      weak_ptr_factory_(this) {
+      weak_ptr_factory_(this),
+      begin_frame_pending_(false) {
   if (CompositorImpl::UsesDirectGL()) {
     surface_texture_transport_.reset(new SurfaceTextureTransportClient());
     layer_ = surface_texture_transport_->Initialize();
     layer_->SetIsDrawable(true);
   } else {
     if (CommandLine::ForCurrentProcess()->HasSwitch(
             switches::kEnableDelegatedRenderer)) {
       delegated_renderer_layer_ = cc::DelegatedRendererLayer::Create(this);
       layer_ = delegated_renderer_layer_;
     } else {
@@ skipping 307 matching lines @@
   if (cached_background_color_ == color)
     return;
 
   cached_background_color_ = color;
   if (content_view_core_)
     content_view_core_->OnBackgroundColorChanged(color);
 }
 
 void RenderWidgetHostViewAndroid::SendBeginFrame(
     base::TimeTicks frame_time) {
-  if (host_)
+  // Throttle the renderer if we are behind. Also only send another beginFrame
+  // if we received a frame for the last beginFrame.
+  if (!ack_callbacks_.empty() || begin_frame_pending_) {
+    if (content_view_core_)
+      content_view_core_->SetVSyncNotificationEnabled(true);
+    return;
+  }
+
+  if (host_) {
+    begin_frame_pending_ = true;
     host_->Send(new ViewMsg_BeginFrame(host_->GetRoutingID(),
                                        frame_time));
+  }
 }
 
 void RenderWidgetHostViewAndroid::OnSetNeedsBeginFrame(
     bool enabled) {

[Sami, 2013/06/04 11:24:55]

We should probably get rid of |enabled| on this message so that there aren't two
parties fighting over the vsync notification state.

   if (content_view_core_)
     content_view_core_->SetVSyncNotificationEnabled(enabled);
 }
 
 void RenderWidgetHostViewAndroid::OnStartContentIntent(
     const GURL& content_url) {
   if (content_view_core_)
     content_view_core_->StartContentIntent(content_url);
 }
 
@@ skipping 156 matching lines @@
   offset.Scale(frame->metadata.device_scale_factor);
   content_size_in_layer_ =
       gfx::Size(texture_size_in_layer_.width() - offset.x(),
                 texture_size_in_layer_.height() - offset.y());
   // Content size changes should be reflected in associated animation effects.
   UpdateAnimationSize(frame);
 }
 
 void RenderWidgetHostViewAndroid::OnSwapCompositorFrame(
     scoped_ptr<cc::CompositorFrame> frame) {
+  begin_frame_pending_ = false;
   // Always let ContentViewCore know about the new frame first, so it can decide
   // to schedule a Draw immediately when it sees the texture layer invalidation.
   if (content_view_core_) {
     // All offsets and sizes are in CSS pixels.
     content_view_core_->UpdateFrameInfo(
         frame->metadata.root_scroll_offset,
         frame->metadata.page_scale_factor,
         gfx::Vector2dF(frame->metadata.min_page_scale_factor,
                        frame->metadata.max_page_scale_factor),
         frame->metadata.root_layer_size,
@@ skipping 400 matching lines @@
 // RenderWidgetHostView, public:
 
 // static
 RenderWidgetHostView*
 RenderWidgetHostView::CreateViewForWidget(RenderWidgetHost* widget) {
   RenderWidgetHostImpl* rwhi = RenderWidgetHostImpl::From(widget);
   return new RenderWidgetHostViewAndroid(rwhi, NULL);
 }
 
 } // namespace content