Add DisplayScheduler to enable BeginFrame-based scheduling of surfaces.

cc/surfaces/display_scheduler.cc

Index: cc/surfaces/display_scheduler.cc
diff --git a/cc/surfaces/display_scheduler.cc b/cc/surfaces/display_scheduler.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ce6b91566bae6fb6e73170f6151aa9ef2cbc5bf8
--- /dev/null
+++ b/cc/surfaces/display_scheduler.cc
@@ -0,0 +1,88 @@
+// Copyright 2014 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 "cc/surfaces/display_scheduler.h"
+
+#include "base/trace_event/trace_event.h"
+#include "cc/output/output_surface.h"
+#include "ui/gfx/frame_time.h"
+
+namespace cc {
+
+DisplayScheduler::DisplayScheduler(
+    OutputSurface* output_surface,
+    Display* display,
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner)
+    : output_surface_(output_surface),
+      display_(display),
+      task_runner_(task_runner),
+      output_surface_lost_(false),
+      need_draw_(false),
+      pending_frames_(0),
+      weak_ptr_factory_(this) {
+  begin_frame_source_ = SyntheticBeginFrameSource::Create(
+      task_runner_.get(), gfx::FrameTime::Now(),
+      BeginFrameArgs::DefaultInterval());
+  begin_frame_source_->AddObserver(this);
+}
+
+DisplayScheduler::~DisplayScheduler() {
+}
+
+void DisplayScheduler::CommitVSyncParameters(base::TimeTicks timebase,
+                                             base::TimeDelta interval) {
+  if (begin_frame_source_ && interval != base::TimeDelta())
+    begin_frame_source_->OnUpdateVSyncParameters(timebase, interval);
+}
+
+void DisplayScheduler::DisplayDamaged() {
+  TRACE_EVENT0("cc", "DisplayScheduler::DisplayDamaged");
+  begin_frame_source_->SetNeedsBeginFrames(!output_surface_lost_);
+  need_draw_ = true;
+}
+
+void DisplayScheduler::OutputSurfaceLost() {
+  output_surface_lost_ = true;
+  begin_frame_source_->SetNeedsBeginFrames(false);
+}
+
+void DisplayScheduler::Draw() {
+  TRACE_EVENT0("cc", "DisplayScheduler::Draw");
+  if (!need_draw_) {
+    begin_frame_source_->SetNeedsBeginFrames(false);
+    return;
+  }
+  if (pending_frames_ >= display_->GetMaxFramesPending())
+    return;
+  if (output_surface_lost_)
+    return;
+  need_draw_ = false;
+  base::TimeTicks start_time = gfx::FrameTime::Now();
+  display_->Draw();
+}
+
+void DisplayScheduler::OnBeginFrame(const BeginFrameArgs& args) {
+  TRACE_EVENT0("cc", "DisplayScheduler::OnBeginFrame");
+  current_begin_frame_args_ = args;
+  // TODO(jbauman): Use deadline to schedule draw.
+  task_runner_->PostTask(FROM_HERE, base::Bind(&DisplayScheduler::Draw,
+                                               weak_ptr_factory_.GetWeakPtr()));
+}
+
+const BeginFrameArgs DisplayScheduler::LastUsedBeginFrameArgs() const {
+  return current_begin_frame_args_;
+}
+
+void DisplayScheduler::AsValueInto(base::trace_event::TracedValue* dict) const {
+}
+
+void DisplayScheduler::DidSwapBuffers() {
+  pending_frames_++;
+}
+
+void DisplayScheduler::DidSwapBuffersComplete() {
+  pending_frames_--;
+}
+
+}  // namespace cc