cc: Support --disable-gpu-vsync with DisplayScheduler

This gives the DisplayScheduler an unthrottled BeginFrameSource
if --disable-gpu-vsync was passed to the command line.

BUG=467750, 491387
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1144073003

Cr-Commit-Position: refs/heads/master@{#331728}

2 files changed, 26 insertions, 9 deletions

diff --git a/cc/surfaces/onscreen_display_client.cc b/cc/surfaces/onscreen_display_client.cc
index 6fc63ce..83db365 100644
--- a/cc/surfaces/onscreen_display_client.cc
+++ b/cc/surfaces/onscreen_display_client.cc
@@ -6,6 +6,7 @@
 
 #include "base/trace_event/trace_event.h"
 #include "cc/output/output_surface.h"
+#include "cc/output/vsync_parameter_observer.h"
 #include "cc/scheduler/begin_frame_source.h"
 #include "cc/surfaces/display_scheduler.h"
 #include "cc/surfaces/surface_display_output_surface.h"
@@ -27,8 +28,10 @@ OnscreenDisplayClient::OnscreenDisplayClient(
                            bitmap_manager,
                            gpu_memory_buffer_manager,
                            settings)),
+      vsync_observer_(nullptr),
       task_runner_(task_runner),
-      output_surface_lost_(false) {
+      output_surface_lost_(false),
+      disable_gpu_vsync_(settings.disable_gpu_vsync) {
 }
 
 OnscreenDisplayClient::~OnscreenDisplayClient() {
@@ -40,11 +43,21 @@ bool OnscreenDisplayClient::Initialize() {
   if (max_frames_pending <= 0)
     max_frames_pending = OutputSurface::DEFAULT_MAX_FRAMES_PENDING;
 
-  synthetic_begin_frame_source_ = SyntheticBeginFrameSource::Create(
-      task_runner_.get(), base::TimeTicks(), BeginFrameArgs::DefaultInterval());
+  if (disable_gpu_vsync_) {
+    begin_frame_source_ =
+        BackToBackBeginFrameSource::Create(task_runner_.get());
+  } else {
+    scoped_ptr<SyntheticBeginFrameSource> synthetic_source =
+        SyntheticBeginFrameSource::Create(task_runner_.get(), base::TimeTicks(),
+                                          BeginFrameArgs::DefaultInterval());
+    vsync_observer_ = synthetic_source.get();
+    begin_frame_source_ = synthetic_source.Pass();
+  }
+
   scheduler_.reset(new DisplayScheduler(display_.get(),
-                                        synthetic_begin_frame_source_.get(),
-                                        task_runner_, max_frames_pending));
+                                        begin_frame_source_.get(), task_runner_,
+                                        max_frames_pending));
+
   return display_->Initialize(output_surface_.Pass(), scheduler_.get());
 }
 
@@ -56,8 +69,8 @@ void OnscreenDisplayClient::CommitVSyncParameters(base::TimeTicks timebase,
   }
 
   surface_display_output_surface_->ReceivedVSyncParameters(timebase, interval);
-  if (synthetic_begin_frame_source_)
-    synthetic_begin_frame_source_->OnUpdateVSyncParameters(timebase, interval);
+  if (vsync_observer_)
+    vsync_observer_->OnUpdateVSyncParameters(timebase, interval);
 }
 
 void OnscreenDisplayClient::OutputSurfaceLost() {
diff --git a/cc/surfaces/onscreen_display_client.h b/cc/surfaces/onscreen_display_client.h
index c042c1b..ec147df 100644
--- a/cc/surfaces/onscreen_display_client.h
+++ b/cc/surfaces/onscreen_display_client.h
@@ -14,12 +14,14 @@
 #include "cc/surfaces/display.h"
 #include "cc/surfaces/surfaces_export.h"
 
+class VSyncParameterObserver;
+
 namespace cc {
+class BeginFrameSource;
 class ContextProvider;
 class DisplayScheduler;
 class SurfaceManager;
 class SurfaceDisplayOutputSurface;
-class SyntheticBeginFrameSource;
 
 // This class provides a DisplayClient implementation for drawing directly to an
 // onscreen context.
@@ -52,11 +54,13 @@ class CC_SURFACES_EXPORT OnscreenDisplayClient
  protected:
   scoped_ptr<OutputSurface> output_surface_;
   scoped_ptr<Display> display_;
-  scoped_ptr<SyntheticBeginFrameSource> synthetic_begin_frame_source_;
+  VSyncParameterObserver* vsync_observer_;
+  scoped_ptr<BeginFrameSource> begin_frame_source_;
   scoped_ptr<DisplayScheduler> scheduler_;
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
   SurfaceDisplayOutputSurface* surface_display_output_surface_;
   bool output_surface_lost_;
+  bool disable_gpu_vsync_;
 
   DISALLOW_COPY_AND_ASSIGN(OnscreenDisplayClient);
 };