Disable scheduler deadline task on battery power in Windows

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/debug/trace_event.h"
 #include "base/debug/trace_event_argument.h"
@@ skipping 99 matching lines @@
 
   // Primary frame source
   primary_frame_source_ =
       frame_sources_constructor->ConstructPrimaryFrameSource(this);
   frame_source_->AddSource(primary_frame_source_);
 
   // Background ticking frame source
   background_frame_source_ =
       frame_sources_constructor->ConstructBackgroundFrameSource(this);
   frame_source_->AddSource(background_frame_source_);
+
+  SetupPowerMonitoring();
 }
 
 Scheduler::~Scheduler() {
+  TeardownPowerMonitoring();
 }
 
 base::TimeTicks Scheduler::Now() const {
   base::TimeTicks now = gfx::FrameTime::Now();
   TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler.now"),
                "Scheduler::Now",
                "now",
                now);
   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.
   if (interval == base::TimeDelta())
     interval = BeginFrameArgs::DefaultInterval();
 
   if (vsync_observer_)
     vsync_observer_->OnUpdateVSyncParameters(timebase, interval);
 }
 
@@ skipping 338 matching lines @@
                "args",
                args.AsValue(),
                "main_thread_is_high_latency",
                main_thread_is_in_high_latency_mode);
   TRACE_COUNTER1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
                  "MainThreadLatency",
                  main_thread_is_in_high_latency_mode);
   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();
 
   base::TimeDelta draw_duration_estimate = client_->DrawDurationEstimate();
   begin_impl_frame_args_ = args;
   begin_impl_frame_args_.deadline -= draw_duration_estimate;
 
   if (!state_machine_.impl_latency_takes_priority() &&
       main_thread_is_in_high_latency_mode &&
       CanCommitAndActivateBeforeDeadline()) {
     state_machine_.SetSkipNextBeginMainFrameToReduceLatency();
   }
 
   client_->WillBeginImplFrame(begin_impl_frame_args_);
   state_machine_.OnBeginImplFrame(begin_impl_frame_args_);
   devtools_instrumentation::DidBeginFrame(layer_tree_host_id_);
 
   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.
     return base::TimeTicks();
   } else if (state_machine_.needs_redraw()) {
     // We have an animation or fast input path on the impl thread that wants
     // to draw, so don't wait too long for a new active tree.
     return args.deadline - draw_duration_estimate;
   } else {
     // The impl thread doesn't have anything it wants to draw and we are just
     // waiting for a new active tree, so post the deadline for the next
     // expected BeginImplFrame start. This allows us to draw immediately when
     // there is a new active tree, instead of waiting for the next
     // BeginImplFrame.
     // TODO(brianderson): Handle long deadlines (that are past the next frame's
     // frame time) properly instead of using this hack.
     return args.frame_time + args.interval;
   }
 }
 
 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_);
 
   base::TimeDelta delta = deadline - Now();
   if (delta <= base::TimeDelta())
     delta = base::TimeDelta();
   task_runner_->PostDelayedTask(
       FROM_HERE, begin_impl_frame_deadline_task_.callback(), delta);
 }
 
@@ skipping 176 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