Hook up ui::Compositor to Display's BeginFrameSource

components/mus/surfaces/direct_output_surface.cc

Index: components/mus/surfaces/direct_output_surface.cc
diff --git a/components/mus/surfaces/direct_output_surface.cc b/components/mus/surfaces/direct_output_surface.cc
index 87009008ad87bd5d87ddb64a81a123c812671620..da6b35e4605d76b3aaee7b83ce7d42e141ea6255 100644
--- a/components/mus/surfaces/direct_output_surface.cc
+++ b/components/mus/surfaces/direct_output_surface.cc
@@ -16,8 +16,15 @@
 namespace mus {
 
 DirectOutputSurface::DirectOutputSurface(
-    const scoped_refptr<cc::ContextProvider>& context_provider)
-    : cc::OutputSurface(context_provider), weak_ptr_factory_(this) {}
+    scoped_refptr<SurfacesContextProvider> context_provider,
+    base::SingleThreadTaskRunner* task_runner)
+    : cc::OutputSurface(context_provider),
+      synthetic_begin_frame_source_(new cc::SyntheticBeginFrameSource(
+          task_runner,
+          cc::BeginFrameArgs::DefaultInterval())),
+      weak_ptr_factory_(this) {
+  context_provider->SetDelegate(this);
+}
 
 DirectOutputSurface::~DirectOutputSurface() {}
 
@@ -25,6 +32,8 @@ bool DirectOutputSurface::BindToClient(cc::OutputSurfaceClient* client) {
   if (!cc::OutputSurface::BindToClient(client))
     return false;
 
+  client->SetBeginFrameSource(synthetic_begin_frame_source_.get());
+
   if (capabilities_.uses_default_gl_framebuffer) {
     capabilities_.flipped_output_surface =
         context_provider()->ContextCapabilities().gpu.flips_vertically;
@@ -32,6 +41,20 @@ bool DirectOutputSurface::BindToClient(cc::OutputSurfaceClient* client) {
   return true;
 }
 
+void DirectOutputSurface::OnVSyncParametersUpdated(int64_t timebase,
+                                                   int64_t interval) {
+  auto timebase_time_ticks = base::TimeTicks::FromInternalValue(timebase);

[sunnyps, 2016/04/01 22:35:25]

nit: Don't really need the _time_ticks and _time_delta suffixes.

[enne (OOO), 2016/04/02 00:18:38]

This code was moved from TopLevelDisplayClient, and those suffixes differentiate
from the function parameters.  Do you have a suggestion on what I should call
this if you don't like this code?

[sunnyps, 2016/04/02 00:47:15]

ah, ok nvm.

+  auto interval_time_delta = base::TimeDelta::FromInternalValue(interval);
+
+  if (interval_time_delta.is_zero()) {
+    // TODO(brianderson): We should not be receiving 0 intervals.
+    interval_time_delta = cc::BeginFrameArgs::DefaultInterval();
+  }
+
+  synthetic_begin_frame_source_->OnUpdateVSyncParameters(timebase_time_ticks,
+                                                         interval_time_delta);
+}
+
 void DirectOutputSurface::SwapBuffers(cc::CompositorFrame* frame) {
   DCHECK(context_provider_);
   DCHECK(frame->gl_frame_data);