Read compositor VSync information from platform, when possible

content/renderer/gpu/compositor_output_surface.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/renderer/gpu/compositor_output_surface.h"
 
 #include "base/command_line.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/compositor_frame_ack.h"
@@ skipping 120 matching lines @@
   }
 
   OutputSurface::SwapBuffers(frame);
 }
 
 void CompositorOutputSurface::OnMessageReceived(const IPC::Message& message) {
   DCHECK(CalledOnValidThread());
   if (!HasClient())
     return;
   IPC_BEGIN_MESSAGE_MAP(CompositorOutputSurface, message)
-    IPC_MESSAGE_HANDLER(ViewMsg_UpdateVSyncParameters, OnUpdateVSyncParameters);
+    IPC_MESSAGE_HANDLER(ViewMsg_UpdateVSyncParameters,
+                        OnUpdateVSyncParametersFromView);

[piman, 2014/02/04 04:51:01]

nit: gratuitous rename? Not sure which "FromView" refers to.

[sheu, 2014/02/04 22:01:45]

A little bit convoluted.  See comment in BrowserCompositorOutputSurface.  Short
answer here: because the BrowserCompositorOutputSurface version has been renamed
to OnUpdateVSyncParametersFromGpu().

[piman, 2014/02/04 22:52:54]

Note: BrowserCompositorOutputSurface doesn't derive from
CompositorOutputSurface, so there's no conflict or anything.

"View" in the renderer context usually refers to RenderView or WebView, which is
mostly unrelated to the OutputSurface, so it's weird. We usually name message
handlers after the messages they handle. If you really feel like you need to
rename this, FromBrowser would carry clearer information than FromView.

     IPC_MESSAGE_HANDLER(ViewMsg_SwapCompositorFrameAck, OnSwapAck);
     IPC_MESSAGE_HANDLER(ViewMsg_ReclaimCompositorResources, OnReclaimResources);
 #if defined(OS_ANDROID)
     IPC_MESSAGE_HANDLER(ViewMsg_BeginFrame, OnBeginImplFrame);
 #endif
   IPC_END_MESSAGE_MAP()
 }
 
-void CompositorOutputSurface::OnUpdateVSyncParameters(
+void CompositorOutputSurface::OnUpdateVSyncParametersFromView(
     base::TimeTicks timebase, base::TimeDelta interval) {
   DCHECK(CalledOnValidThread());
-  OnVSyncParametersChanged(timebase, interval);
+  CommitVSyncParameters(timebase, interval);
 }
 
 #if defined(OS_ANDROID)
 void CompositorOutputSurface::SetNeedsBeginImplFrame(bool enable) {
   DCHECK(CalledOnValidThread());
   if (needs_begin_impl_frame_ != enable)
     Send(new ViewHostMsg_SetNeedsBeginFrame(routing_id_, enable));
   OutputSurface::SetNeedsBeginImplFrame(enable);
 }
 
@@ skipping 62 matching lines @@
   // If this is the last surface to stop preferring smoothness,
   // Reset the main thread's priority to the default.
   if (prefers_smoothness_ == true &&
       --g_prefer_smoothness_count == 0) {
     SetThreadPriorityToDefault(main_thread_handle_);
   }
   prefers_smoothness_ = prefers_smoothness;
 }
 
 }  // namespace content