Purge memory before suspending timer queues when backgrounded.

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index 45678d19a939b0bec6864ddc6aca43a1d66fc21f..5f7e5ae4773bd265ddddeb2d49b8761ebcd52d38 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -898,6 +898,12 @@ void RenderThreadImpl::Init(
       base::Bind(&RenderThreadImpl::RecordPurgeAndSuspendMemoryGrowthMetrics,
                  base::Unretained(this)));
 
+  purge_before_suspend_timers_closure_.Reset(base::Bind(
+      &RenderThreadImpl::PurgeBeforeSuspendTimerQueue, base::Unretained(this)));
+  suspend_timers_when_backgrounded_closure_.Reset(
+      base::Bind(&RenderThreadImpl::SuspendTimerQueueWhenBackgrounded,
+                 base::Unretained(this)));
+
   base::MemoryCoordinatorClientRegistry::GetInstance()->Register(this);
 
   // If this renderer doesn't run inside the browser process, enable
@@ -1203,11 +1209,6 @@ void RenderThreadImpl::InitializeWebKit(
     isolate->IsolateInBackgroundNotification();
   }
 
-  renderer_scheduler_->SetTimerQueueSuspensionWhenBackgroundedEnabled(
-      GetContentClient()
-          ->renderer()
-          ->AllowTimerSuspensionWhenProcessBackgrounded());
-
   SkGraphics::SetResourceCacheSingleAllocationByteLimit(
       kImageCacheSingleAllocationByteLimit);
 
@@ -1641,8 +1642,29 @@ void RenderThreadImpl::OnProcessBackgrounded(bool backgrounded) {
 
   if (backgrounded) {
     renderer_scheduler_->OnRendererBackgrounded();
+
+    if (GetContentClient()
+            ->renderer()
+            ->AllowTimerSuspensionWhenProcessBackgrounded()) {
+      base::TimeDelta suspend_timers_when_backgrounded_delay =
+          base::TimeDelta::FromMilliseconds(
+              kSuspendTimersWhenBackgroundedDelayMillis);
+      GetRendererScheduler()->DefaultTaskRunner()->PostDelayedTask(
+          FROM_HERE, purge_before_suspend_timers_closure_.callback(),
+          suspend_timers_when_backgrounded_delay);
+    }
   } else {
     renderer_scheduler_->OnRendererForegrounded();
+
+    purge_before_suspend_timers_closure_.Cancel();
+    purge_before_suspend_timers_closure_.Reset(
+        base::Bind(&RenderThreadImpl::PurgeBeforeSuspendTimerQueue,
+                   base::Unretained(this)));
+    suspend_timers_when_backgrounded_closure_.Cancel();
+    suspend_timers_when_backgrounded_closure_.Reset(
+        base::Bind(&RenderThreadImpl::SuspendTimerQueueWhenBackgrounded,
+                   base::Unretained(this)));
+
     // TODO(tasak): after enabling MemoryCoordinator, remove this Notify
     // and follow MemoryCoordinator's request.
     if (base::FeatureList::IsEnabled(features::kPurgeAndSuspend))
@@ -1660,6 +1682,24 @@ void RenderThreadImpl::OnProcessBackgrounded(bool backgrounded) {
   }
 }
 
+void RenderThreadImpl::PurgeBeforeSuspendTimerQueue() {

[haraken, 2017/02/02 08:53:12]

PurgeBeforeSuspendTimerQueue => PurgeAndSuspendTimerQueueWhenBackgrounded

[tasak, 2017/02/03 03:13:14]

Done.

+  DCHECK(IsMainThread());
+  if (!RendererIsHidden())
+    return;
+  base::MemoryCoordinatorClientRegistry::GetInstance()->Notify(
+      base::MemoryState::SUSPENDED);

[haraken, 2017/02/02 08:53:13]

You don't need to do this in this CL but we want to add a UMA to measure the
memory impact of the purging.

[tasak, 2017/02/03 03:13:14]

Acknowledged.

+  GetRendererScheduler()->DefaultTaskRunner()->PostDelayedTask(
+      FROM_HERE, suspend_timers_when_backgrounded_closure_.callback(),
+      base::TimeDelta::FromSeconds(5));

[haraken, 2017/02/02 08:53:13]

Add a comment and mention why this delay is needed.

[tasak, 2017/02/03 03:13:14]

Done.

+}
+
+void RenderThreadImpl::SuspendTimerQueueWhenBackgrounded() {
+  DCHECK(IsMainThread());
+  if (!RendererIsHidden())
+    return;
+  renderer_scheduler_->SuspendRenderer();
+}
+
 void RenderThreadImpl::OnProcessPurgeAndSuspend() {
   ChildThreadImpl::OnProcessPurgeAndSuspend();
   if (!RendererIsHidden())