Add BeginFrameObserverProxy

content/browser/renderer_host/begin_frame_observer_proxy.cc

Index: content/browser/renderer_host/begin_frame_observer_proxy.cc
diff --git a/content/browser/renderer_host/begin_frame_observer_proxy.cc b/content/browser/renderer_host/begin_frame_observer_proxy.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7a6651f53c3a9faf6d55e981e1838d333563dd5a
--- /dev/null
+++ b/content/browser/renderer_host/begin_frame_observer_proxy.cc
@@ -0,0 +1,70 @@
+// Copyright 2015 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/browser/renderer_host/begin_frame_observer_proxy.h"
+
+namespace content {
+
+BeginFrameObserverProxy::BeginFrameObserverProxy(
+    BeginFrameObserverProxyClient* client)
+    : needs_begin_frames_(false),
+      client_(client),
+      compositor_(nullptr) {
+}
+
+BeginFrameObserverProxy::~BeginFrameObserverProxy() {
+}
+
+void BeginFrameObserverProxy::SetNeedsBeginFrames(bool needs_begin_frames) {
+  if (needs_begin_frames_ == needs_begin_frames)
+    return;
+
+  needs_begin_frames_ = needs_begin_frames;
+
+  // In some cases, BeginFrame message is requested before |client_|'s window is
+  // added in the root window hierarchy.
+  if (!compositor_)
+    return;
+
+  if (needs_begin_frames)
+    StartObservingBeginFrames();
+  else
+    StopObservingBeginFrames();
+}
+
+void BeginFrameObserverProxy::SetCompositor(ui::Compositor* compositor) {
+  DCHECK(!compositor_);
+  DCHECK(compositor);
+
+  compositor_ = compositor;
+  if (needs_begin_frames_)
+    StartObservingBeginFrames();
+}
+
+void BeginFrameObserverProxy::ResetCompositor() {
+  if (!compositor_)
+    return;
+
+  if (needs_begin_frames_)
+    StopObservingBeginFrames();
+  compositor_ = nullptr;
+}
+
+void BeginFrameObserverProxy::OnSendBeginFrame(const cc::BeginFrameArgs& args) {
+  if (last_sent_begin_frame_args_.frame_time != args.frame_time)
+    client_->SendBeginFrame(args);
+  last_sent_begin_frame_args_ = args;
+}
+
+void BeginFrameObserverProxy::StartObservingBeginFrames() {
+  DCHECK(compositor_);
+  compositor_->AddBeginFrameObserver(this);
+}
+
+void BeginFrameObserverProxy::StopObservingBeginFrames() {
+  DCHECK(compositor_);
+  compositor_->RemoveBeginFrameObserver(this);
+}
+
+}  // namespace content