NOT FOR COMMIT: Move background pausing to the WebView level

third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc

Index: third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc b/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
index f3369ecb1d37ebb10a89938fb290bf28bd1e0067..823edb8a1d167e82738ddab15e13d30d3af80014 100644
--- a/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
+++ b/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
@@ -119,10 +119,6 @@ RendererSchedulerImpl::RendererSchedulerImpl(
   end_renderer_hidden_idle_period_closure_.Reset(base::Bind(
       &RendererSchedulerImpl::EndIdlePeriod, weak_factory_.GetWeakPtr()));
 
-  suspend_timers_when_backgrounded_closure_.Reset(
-      base::Bind(&RendererSchedulerImpl::SuspendTimerQueueWhenBackgrounded,
-                 weak_factory_.GetWeakPtr()));
-
   default_loading_task_queue_ =
       NewLoadingTaskQueue(TaskQueue::QueueType::DEFAULT_LOADING);
   default_timer_task_queue_ =
@@ -202,9 +198,6 @@ RendererSchedulerImpl::MainThreadOnly::MainThreadOnly(
       expensive_task_policy(ExpensiveTaskPolicy::RUN),
       renderer_hidden(false),
       renderer_backgrounded(false),
-      renderer_suspended(false),
-      timer_queue_suspension_when_backgrounded_enabled(false),
-      timer_queue_suspended_when_backgrounded(false),
       was_shutdown(false),
       loading_tasks_seem_expensive(false),
       timer_tasks_seem_expensive(false),
@@ -530,17 +523,6 @@ void RendererSchedulerImpl::OnRendererBackgrounded() {
   base::TimeTicks now = tick_clock()->NowTicks();
   GetMainThreadOnly().foreground_main_thread_load_tracker.Pause(now);
   GetMainThreadOnly().background_main_thread_load_tracker.Resume(now);
-
-  if (!GetMainThreadOnly().timer_queue_suspension_when_backgrounded_enabled)
-    return;
-
-  suspend_timers_when_backgrounded_closure_.Cancel();
-  base::TimeDelta suspend_timers_when_backgrounded_delay =
-      base::TimeDelta::FromMilliseconds(
-          kSuspendTimersWhenBackgroundedDelayMillis);
-  control_task_queue_->PostDelayedTask(
-      FROM_HERE, suspend_timers_when_backgrounded_closure_.GetCallback(),
-      suspend_timers_when_backgrounded_delay);
 }
 
 void RendererSchedulerImpl::OnRendererForegrounded() {
@@ -551,16 +533,12 @@ void RendererSchedulerImpl::OnRendererForegrounded() {
     return;
 
   GetMainThreadOnly().renderer_backgrounded = false;
-  GetMainThreadOnly().renderer_suspended = false;
 
   UpdatePolicy();
 
   base::TimeTicks now = tick_clock()->NowTicks();
   GetMainThreadOnly().foreground_main_thread_load_tracker.Resume(now);
   GetMainThreadOnly().background_main_thread_load_tracker.Pause(now);
-
-  suspend_timers_when_backgrounded_closure_.Cancel();
-  ResumeTimerQueueWhenForegroundedOrResumed();
 }
 
 void RendererSchedulerImpl::OnAudioStateChanged() {
@@ -580,34 +558,6 @@ void RendererSchedulerImpl::OnAudioStateChanged() {
   UpdatePolicy();
 }
 
-void RendererSchedulerImpl::SuspendRenderer() {
-  helper_.CheckOnValidThread();
-  if (helper_.IsShutdown())
-    return;
-  if (!GetMainThreadOnly().renderer_backgrounded)
-    return;
-  suspend_timers_when_backgrounded_closure_.Cancel();
-
-  UMA_HISTOGRAM_COUNTS("PurgeAndSuspend.PendingTaskCount",
-                       helper_.GetNumberOfPendingTasks());
-
-  // TODO(hajimehoshi): We might need to suspend not only timer queue but also
-  // e.g. loading tasks or postMessage.
-  GetMainThreadOnly().renderer_suspended = true;
-  SuspendTimerQueueWhenBackgrounded();
-}
-
-void RendererSchedulerImpl::ResumeRenderer() {
-  helper_.CheckOnValidThread();
-  if (helper_.IsShutdown())
-    return;
-  if (!GetMainThreadOnly().renderer_backgrounded)
-    return;
-  suspend_timers_when_backgrounded_closure_.Cancel();
-  GetMainThreadOnly().renderer_suspended = false;
-  ResumeTimerQueueWhenForegroundedOrResumed();
-}
-
 void RendererSchedulerImpl::EndIdlePeriod() {
   if (GetMainThreadOnly().in_idle_period_for_testing)
     return;
@@ -1108,18 +1058,12 @@ void RendererSchedulerImpl::UpdatePolicyLocked(UpdateType update_type) {
   }
   GetMainThreadOnly().expensive_task_policy = expensive_task_policy;
 
-  if (GetMainThreadOnly().timer_queue_suspend_count != 0 ||
-      GetMainThreadOnly().timer_queue_suspended_when_backgrounded) {
+  if (GetMainThreadOnly().timer_queue_suspend_count != 0) {
     new_policy.timer_queue_policy.is_enabled = false;
     // TODO(alexclarke): Figure out if we really need to do this.
     new_policy.timer_queue_policy.time_domain_type = TimeDomainType::REAL;
   }
 
-  if (GetMainThreadOnly().renderer_suspended) {
-    new_policy.loading_queue_policy.is_enabled = false;
-    DCHECK(!new_policy.timer_queue_policy.is_enabled);
-  }
-
   if (GetMainThreadOnly().use_virtual_time) {
     new_policy.compositor_queue_policy.time_domain_type =
         TimeDomainType::VIRTUAL;
@@ -1371,13 +1315,6 @@ void RendererSchedulerImpl::ResumeTimerQueue() {
   ForceUpdatePolicy();
 }
 
-void RendererSchedulerImpl::SetTimerQueueSuspensionWhenBackgroundedEnabled(
-    bool enabled) {
-  // Note that this will only take effect for the next backgrounded signal.
-  GetMainThreadOnly().timer_queue_suspension_when_backgrounded_enabled =
-      enabled;
-}
-
 std::unique_ptr<base::trace_event::ConvertableToTraceFormat>
 RendererSchedulerImpl::AsValue(base::TimeTicks optional_now) const {
   base::AutoLock lock(any_thread_lock_);
@@ -1452,9 +1389,6 @@ RendererSchedulerImpl::AsValueLocked(base::TimeTicks optional_now) const {
       GetMainThreadOnly().have_reported_blocking_intervention_since_navigation);
   state->SetBoolean("renderer_backgrounded",
                     GetMainThreadOnly().renderer_backgrounded);
-  state->SetBoolean(
-      "timer_queue_suspended_when_backgrounded",
-      GetMainThreadOnly().timer_queue_suspended_when_backgrounded);
   state->SetInteger("timer_queue_suspend_count",
                     GetMainThreadOnly().timer_queue_suspend_count);
   state->SetDouble("now", (optional_now - base::TimeTicks()).InMillisecondsF());
@@ -1603,27 +1537,6 @@ void RendererSchedulerImpl::OnFirstMeaningfulPaint() {
   UpdatePolicyLocked(UpdateType::MAY_EARLY_OUT_IF_POLICY_UNCHANGED);
 }
 
-void RendererSchedulerImpl::SuspendTimerQueueWhenBackgrounded() {
-  DCHECK(GetMainThreadOnly().renderer_backgrounded);
-  if (GetMainThreadOnly().timer_queue_suspended_when_backgrounded)
-    return;
-
-  GetMainThreadOnly().timer_queue_suspended_when_backgrounded = true;
-  ForceUpdatePolicy();
-  Platform::Current()->RequestPurgeMemory();
-}
-
-void RendererSchedulerImpl::ResumeTimerQueueWhenForegroundedOrResumed() {
-  DCHECK(!GetMainThreadOnly().renderer_backgrounded ||
-         (GetMainThreadOnly().renderer_backgrounded &&
-          !GetMainThreadOnly().renderer_suspended));
-  if (!GetMainThreadOnly().timer_queue_suspended_when_backgrounded)
-    return;
-
-  GetMainThreadOnly().timer_queue_suspended_when_backgrounded = false;
-  ForceUpdatePolicy();
-}
-
 void RendererSchedulerImpl::ResetForNavigationLocked() {
   helper_.CheckOnValidThread();
   any_thread_lock_.AssertAcquired();
@@ -1737,8 +1650,7 @@ void RendererSchedulerImpl::OnTriedToExecuteBlockedTask(
   if (GetMainThreadOnly().current_use_case == UseCase::TOUCHSTART ||
       GetMainThreadOnly().longest_jank_free_task_duration <
           base::TimeDelta::FromMilliseconds(kRailsResponseTimeMillis) ||
-      GetMainThreadOnly().timer_queue_suspend_count ||
-      GetMainThreadOnly().timer_queue_suspended_when_backgrounded) {
+      GetMainThreadOnly().timer_queue_suspend_count) {
     return;
   }
   if (!GetMainThreadOnly().timer_tasks_seem_expensive &&