Unified BeginFrame scheduling

cc/scheduler/begin_frame_manager.cc

+// 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/scheduler/begin_frame_manager.h"
+
+namespace cc {
+
+BeginFrameManager::BeginFrameManager() : delegate_(NULL),
+                                         num_of_observers_(0) {}
+
+BeginFrameManager::~BeginFrameManager() {
+  DCHECK_EQ(0, num_of_observers_);
+}
+
+void BeginFrameManager::SendBeginFrameToChildren(const BeginFrameArgs& args) {
+  DCHECK(CalledOnValidThread());
+  FOR_EACH_OBSERVER(Observer,
+                    observer_list_,
+                    OnSendBeginFrame(args));
+  last_begin_frame_args_ = args;
+}
+
+void BeginFrameManager::SetAuthoritativeVSyncInterval(
+    base::TimeDelta interval) const {
+  DCHECK(delegate_);
+  delegate_->SetAuthoritativeVSyncInterval(interval);
+}
+
+void BeginFrameManager::AddObserver(
+    Observer* observer,
+    const BeginFrameArgs& last_begin_frame_args_sent_to_observer) {
+  DCHECK(CalledOnValidThread());
+  DCHECK_GE(num_of_observers_, 0);
+
+  observer_list_.AddObserver(observer);
+  if (++num_of_observers_ == 1)
+    delegate_->SetChildrenNeedBeginFrames(true);
+
+  // If |last_begin_frame_args_| is still effective, send it to the new
+  // |observer| immediately.
+  if (!last_begin_frame_args_sent_to_observer.deadline.is_null() &&
+      last_begin_frame_args_sent_to_observer != last_begin_frame_args_ &&
+      last_begin_frame_args_.deadline > base::TimeTicks::Now())
+    observer->OnSendBeginFrame(last_begin_frame_args_);
+}
+
+void BeginFrameManager::RemoveObserver(Observer* observer) {
+  DCHECK(CalledOnValidThread());
+  DCHECK_GE(num_of_observers_, 1);
+
+  observer_list_.RemoveObserver(observer);
+  if (--num_of_observers_ == 0)
+    delegate_->SetChildrenNeedBeginFrames(false);
+}
+
+}  // namespace cc