cc: Add support for handling authoritative vsync interval

cc/scheduler/scheduler.cc

 // Copyright 2011 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/scheduler.h"
 
 #include <algorithm>
 
 #include "base/auto_reset.h"
 #include "base/logging.h"
@@ skipping 69 matching lines @@
     int layer_tree_host_id,
     const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
     scoped_ptr<BeginFrameSource> external_begin_frame_source,
     SchedulerFrameSourcesConstructor* frame_sources_constructor)
     : frame_source_(),
       primary_frame_source_(NULL),
       background_frame_source_(NULL),
       primary_frame_source_internal_(external_begin_frame_source.Pass()),
       background_frame_source_internal_(),
       vsync_observer_(NULL),
+      authoritative_vsync_interval_(base::TimeDelta()),
+      last_vsync_timebase_(base::TimeTicks()),
       throttle_frame_production_(scheduler_settings.throttle_frame_production),
       settings_(scheduler_settings),
       client_(client),
       layer_tree_host_id_(layer_tree_host_id),
       task_runner_(task_runner),
       state_machine_(scheduler_settings),
       inside_process_scheduled_actions_(false),
       inside_action_(SchedulerStateMachine::ACTION_NONE),
       weak_factory_(this) {
   TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
@@ skipping 41 matching lines @@
   base::TimeTicks now = gfx::FrameTime::Now();
   TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler.now"),
                "Scheduler::Now",
                "now",
                now);
   return now;
 }
 
 void Scheduler::CommitVSyncParameters(base::TimeTicks timebase,
                                       base::TimeDelta interval) {
-  // TODO(brianderson): We should not be receiving 0 intervals.
-  if (interval == base::TimeDelta())
+  if (authoritative_vsync_interval_ != base::TimeDelta()) {
+    interval = authoritative_vsync_interval_;
+  } else if (interval == base::TimeDelta()) {
+    // TODO(brianderson): We should not be receiving 0 intervals.
     interval = BeginFrameArgs::DefaultInterval();
+  }
+
+  last_vsync_timebase_ = timebase;
 
   if (vsync_observer_)
     vsync_observer_->OnUpdateVSyncParameters(timebase, interval);
 }
 
 void Scheduler::SetEstimatedParentDrawTime(base::TimeDelta draw_time) {
   DCHECK_GE(draw_time.ToInternalValue(), 0);
   estimated_parent_draw_time_ = draw_time;
 }
 
@@ skipping 260 matching lines @@
     BeginImplFrame(adjusted_args);
   }
   return true;
 }
 
 void Scheduler::SetChildrenNeedBeginFrames(bool children_need_begin_frames) {
   state_machine_.SetChildrenNeedBeginFrames(children_need_begin_frames);
   ProcessScheduledActions();
 }
 
+void Scheduler::SetAuthoritativeVSyncInterval(const base::TimeDelta& interval) {
+  authoritative_vsync_interval_ = interval;
+  if (vsync_observer_)
+    vsync_observer_->OnUpdateVSyncParameters(last_vsync_timebase_, interval);
+}
+
 // BeginRetroFrame is called for BeginFrames that we've deferred because
 // the scheduler was in the middle of processing a previous BeginFrame.
 void Scheduler::BeginRetroFrame() {
   TRACE_EVENT0("cc,benchmark", "Scheduler::BeginRetroFrame");
   DCHECK(!settings_.using_synchronous_renderer_compositor);
   DCHECK(!begin_retro_frame_args_.empty());
   DCHECK(!begin_retro_frame_task_.IsCancelled());
   DCHECK_EQ(state_machine_.begin_impl_frame_state(),
             SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE);
 
@@ skipping 385 matching lines @@
 }
 
 bool Scheduler::IsBeginMainFrameSentOrStarted() const {
   return (state_machine_.commit_state() ==
               SchedulerStateMachine::COMMIT_STATE_BEGIN_MAIN_FRAME_SENT ||
           state_machine_.commit_state() ==
               SchedulerStateMachine::COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED);
 }
 
 }  // namespace cc