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"
 #include "base/logging.h"
+#include "base/power_monitor/power_monitor.h"
 #include "base/single_thread_task_runner.h"
 #include "cc/debug/devtools_instrumentation.h"
 #include "cc/debug/traced_value.h"
 #include "cc/scheduler/delay_based_time_source.h"
 #include "ui/gfx/frame_time.h"
 
 namespace cc {
 
 Scheduler::SyntheticBeginFrameSource::SyntheticBeginFrameSource(
     Scheduler* scheduler,
@@ skipping 84 matching lines @@
       base::Bind(&Scheduler::BeginRetroFrame, weak_factory_.GetWeakPtr());
   begin_unthrottled_frame_closure_ =
       base::Bind(&Scheduler::BeginUnthrottledFrame, weak_factory_.GetWeakPtr());
   begin_impl_frame_deadline_closure_ = base::Bind(
       &Scheduler::OnBeginImplFrameDeadline, weak_factory_.GetWeakPtr());
   poll_for_draw_triggers_closure_ = base::Bind(
       &Scheduler::PollForAnticipatedDrawTriggers, weak_factory_.GetWeakPtr());
   advance_commit_state_closure_ = base::Bind(
       &Scheduler::PollToAdvanceCommitState, weak_factory_.GetWeakPtr());
 
+  if (settings_.high_latency_mode_on_battery) {
+    SetupPowerMonitoring();
+  }
+
   if (!settings_.begin_frame_scheduling_enabled) {
     SetupSyntheticBeginFrames();
   }
 }
 
 Scheduler::~Scheduler() {
+  if (settings_.high_latency_mode_on_battery) {
+    TeardownPowerMonitoring();
+  }
+
   if (synthetic_begin_frame_source_) {
     synthetic_begin_frame_source_->SetNeedsBeginFrame(false,
                                                       &begin_retro_frame_args_);
   }
 }
 
 void Scheduler::SetupSyntheticBeginFrames() {
   DCHECK(!synthetic_begin_frame_source_);
   synthetic_begin_frame_source_.reset(
       new SyntheticBeginFrameSource(this, task_runner_.get()));
 }
 
+void Scheduler::SetupPowerMonitoring() {
+  base::PowerMonitor* power_monitor = base::PowerMonitor::Get();
+  DCHECK(power_monitor != NULL);
+  power_monitor->AddObserver(this);
+}
+
+void Scheduler::TeardownPowerMonitoring() {
+  base::PowerMonitor* power_monitor = base::PowerMonitor::Get();
+  DCHECK(power_monitor != NULL);
+  power_monitor->RemoveObserver(this);
+}
+
+void Scheduler::OnPowerStateChange(bool on_battery_power) {
+  on_battery_power_ = 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();
   vsync_interval_ = interval;
   if (!settings_.begin_frame_scheduling_enabled)
     synthetic_begin_frame_source_->CommitVSyncParameters(timebase, interval);
 }
 
@@ skipping 346 matching lines @@
   DCHECK(!settings_.using_synchronous_renderer_compositor);
 
   if (state_machine_.begin_impl_frame_state() !=
       SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE)
     return;
 
   begin_retro_frame_posted_ = true;
   task_runner_->PostTask(FROM_HERE, begin_retro_frame_closure_);
 }
 
+bool Scheduler::ShouldPostBeginImplFrameDeadline() {
+  // The synchronous renderer compositor has to make its GL calls
+  // within this call.

[brianderson, 2014/09/09 17:59:05]

this call -> within the BeginFrame call stack.

+  // 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.
+  if (settings_.using_synchronous_renderer_compositor)
+    return false;
+
+  if (settings_.high_latency_mode_on_battery && on_battery_power_)
+    return false;
+
+  // We are ready to draw a new active tree immediately.
+  if (state_machine_.ShouldTriggerBeginImplFrameDeadlineEarly())
+    return false;
+
+  return true;
+}
+
 // BeginImplFrame starts a compositor frame that will wait up until a deadline
 // for a BeginMainFrame+activation to complete before it times out and draws
 // any asynchronous animation and scroll/pinch updates.
 void Scheduler::BeginImplFrame(const BeginFrameArgs& args) {
   TRACE_EVENT1("cc", "Scheduler::BeginImplFrame", "args", args.AsValue());
   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() &&
       state_machine_.MainThreadIsInHighLatencyMode() &&
       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 (ShouldPostBeginImplFrameDeadline()) {
+    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()) {
+  if (state_machine_.needs_redraw()) {

[brianderson, 2014/09/09 17:59:05]

AdjustedBeginImplFrameDeadline is used in more than one place. Are you sure this
won't have side effects with the BeginRetroFrames?

     // 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) {
-  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 - gfx::FrameTime::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