Disable scheduler deadline task on battery power in Windows

cc/scheduler/scheduler.cc

Index: cc/scheduler/scheduler.cc
diff --git a/cc/scheduler/scheduler.cc b/cc/scheduler/scheduler.cc
index 44d7d77ace95b2f839154854882e659ef51feda6..45e3554eca1d1c2116a4f43b7bed3a26df25b478 100644
--- a/cc/scheduler/scheduler.cc
+++ b/cc/scheduler/scheduler.cc
@@ -117,9 +117,12 @@ Scheduler::Scheduler(
   background_frame_source_ =
       frame_sources_constructor->ConstructBackgroundFrameSource(this);
   frame_source_->AddSource(background_frame_source_);
+
+  SetupPowerMonitoring();
 }
 
 Scheduler::~Scheduler() {
+  TeardownPowerMonitoring();
 }
 
 base::TimeTicks Scheduler::Now() const {
@@ -131,6 +134,27 @@ base::TimeTicks Scheduler::Now() const {
   return now;
 }
 
+void Scheduler::SetupPowerMonitoring() {
+  base::PowerMonitor* power_monitor = client_->PowerMonitor();
+  DCHECK_IMPLIES(settings_.prioritize_impl_latency_on_battery,
+                 power_monitor != NULL);

[danakj, 2014/10/09 21:18:02]

!= NULL is redundant here and below

[sunnyps, 2014/10/09 22:04:39]

I don't think it is. The tests which deal the scheduler exclusively setup a fake
scheduler client which returns a valid power monitor however other tests which
rely on the scheduler indirectly (like the layer tree host impl tests) have a
NULL power monitor (since base::PowerMonitor()::Get() returns NULL).

Now that I've changed the code so that we only register with the power monitor
when the settings flag tells us to this redundancy should be gone.

[danakj, 2014/10/09 22:08:27]

Sorry, what I meant is if (a != NULL) is more simply written as if (a)

+  if (power_monitor != NULL) {
+    power_monitor->AddObserver(this);
+    state_machine_.SetOnBatteryPower(power_monitor->IsOnBatteryPower());
+  }
+}
+
+void Scheduler::TeardownPowerMonitoring() {
+  base::PowerMonitor* power_monitor = client_->PowerMonitor();
+  if (power_monitor != NULL) {
+    power_monitor->RemoveObserver(this);
+  }
+}
+
+void Scheduler::OnPowerStateChange(bool on_battery_power) {
+  state_machine_.SetOnBatteryPower(on_battery_power);
+}
+
 void Scheduler::CommitVSyncParameters(base::TimeTicks timebase,
                                       base::TimeDelta interval) {
   // TODO(brianderson): We should not be receiving 0 intervals.
@@ -489,6 +513,7 @@ void Scheduler::BeginImplFrame(const BeginFrameArgs& args) {
   DCHECK_EQ(state_machine_.begin_impl_frame_state(),
             SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE);
   DCHECK(state_machine_.HasInitializedOutputSurface());
+  DCHECK(begin_impl_frame_deadline_task_.IsCancelled());
 
   advance_commit_state_task_.Cancel();
 
@@ -509,15 +534,19 @@ void Scheduler::BeginImplFrame(const BeginFrameArgs& args) {
   ProcessScheduledActions();
 
   state_machine_.OnBeginImplFrameDeadlinePending();
-  ScheduleBeginImplFrameDeadline(
-      AdjustedBeginImplFrameDeadline(args, draw_duration_estimate));
+
+  if (!settings_.using_synchronous_renderer_compositor) {
+    ScheduleBeginImplFrameDeadline(
+        AdjustedBeginImplFrameDeadline(args, draw_duration_estimate));
+  } else {
+    OnBeginImplFrameDeadline();
+  }
 }
 
 base::TimeTicks Scheduler::AdjustedBeginImplFrameDeadline(
     const BeginFrameArgs& args,
     base::TimeDelta draw_duration_estimate) const {
   if (settings_.using_synchronous_renderer_compositor) {
-    // The synchronous compositor needs to draw right away.
     return base::TimeTicks();
   } else if (state_machine_.ShouldTriggerBeginImplFrameDeadlineEarly()) {
     // We are ready to draw a new active tree immediately.
@@ -541,15 +570,6 @@ base::TimeTicks Scheduler::AdjustedBeginImplFrameDeadline(
 void Scheduler::ScheduleBeginImplFrameDeadline(base::TimeTicks deadline) {
   TRACE_EVENT1(
       "cc", "Scheduler::ScheduleBeginImplFrameDeadline", "deadline", deadline);
-  if (settings_.using_synchronous_renderer_compositor) {
-    // The synchronous renderer compositor has to make its GL calls
-    // within this call.
-    // TODO(brianderson): Have the OutputSurface initiate the deadline tasks
-    // so the sychronous renderer compositor can take advantage of splitting
-    // up the BeginImplFrame and deadline as well.
-    OnBeginImplFrameDeadline();
-    return;
-  }
   begin_impl_frame_deadline_task_.Cancel();
   begin_impl_frame_deadline_task_.Reset(begin_impl_frame_deadline_closure_);