[Android] Provide synchronized input flush with BeginFrame

content/browser/renderer_host/render_widget_host_view_android.cc

Index: content/browser/renderer_host/render_widget_host_view_android.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_android.cc b/content/browser/renderer_host/render_widget_host_view_android.cc
index 5ebd7d4aa4abe33eb51cf17a795964d120d129bd..01205d000612b7750ab3336a91e3c615ca638369 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.cc
+++ b/content/browser/renderer_host/render_widget_host_view_android.cc
@@ -114,7 +114,8 @@ RenderWidgetHostViewAndroid::RenderWidgetHostViewAndroid(
       texture_id_in_layer_(0),
       current_mailbox_output_surface_id_(kUndefinedOutputSurfaceId),
       weak_ptr_factory_(this),
-      overscroll_effect_enabled_(true) {
+      overscroll_effect_enabled_(true),
+      flush_input_requested_(false) {
   if (CompositorImpl::UsesDirectGL()) {
     surface_texture_transport_.reset(new SurfaceTextureTransportClient());
     layer_ = surface_texture_transport_->Initialize();
@@ -460,8 +461,16 @@ void RenderWidgetHostViewAndroid::OnDidChangeBodyBackgroundColor(
 void RenderWidgetHostViewAndroid::SendBeginFrame(
     const cc::BeginFrameArgs& args) {
   TRACE_EVENT0("cc", "RenderWidgetHostViewAndroid::SendBeginFrame");
-  if (host_)
-    host_->Send(new ViewMsg_BeginFrame(host_->GetRoutingID(), args));
+  if (!host_)
+    return;
+
+  if (flush_input_requested_) {
+    flush_input_requested_ = false;
+    host_->FlushInput();
+    content_view_core_->RemoveBeginFrameSubscriber();

[brianderson, 2013/09/25 22:23:14]

Is it possible that this class gets destroyed after OnSetNeedsFlushInput but
before we get here?  If so, we should probably check for that case and make sure
we balance the calls in the destructor if we need to.

We should probably do the same thing for OnSetNeedsBeginFrame's subscription as
well.

[jdduke (slow), 2013/09/25 23:31:09]

ContentViewCore will automatically reset any vsync subscribers when this is
destroyed, but you're right that it would be unbalanced otherwise.  

+  }
+
+  host_->Send(new ViewMsg_BeginFrame(host_->GetRoutingID(), args));
 }
 
 void RenderWidgetHostViewAndroid::OnSetNeedsBeginFrame(
@@ -472,7 +481,10 @@ void RenderWidgetHostViewAndroid::OnSetNeedsBeginFrame(
   // we have to make sure calls to ContentViewCoreImpl's SetNeedsBeginFrame

[brianderson, 2013/09/25 22:23:14]

Comment should not refer to SetNeedsBeginFrame anymore.

[jdduke (slow), 2013/09/25 23:31:09]

Done.

   // are balanced, even if RenderWidgetHostViewAndroid's may not be.
   if (content_view_core_ && needs_begin_frame_ != enabled) {
-    content_view_core_->SetNeedsBeginFrame(enabled);
+    if (enabled)
+      content_view_core_->AddBeginFrameSubscriber();
+    else
+      content_view_core_->RemoveBeginFrameSubscriber();
     needs_begin_frame_ = enabled;
   }
 }
@@ -971,6 +983,13 @@ InputEventAckState RenderWidgetHostViewAndroid::FilterInputEvent(
   return INPUT_EVENT_ACK_STATE_NOT_CONSUMED;
 }
 
+void RenderWidgetHostViewAndroid::OnSetNeedsFlushInput() {
+  if (flush_input_requested_)
+    return;
+  flush_input_requested_ = true;
+  content_view_core_->AddBeginFrameSubscriber();
+}
+
 void RenderWidgetHostViewAndroid::OnAccessibilityEvents(
     const std::vector<AccessibilityHostMsg_EventParams>& params) {
   if (!host_ ||