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..0ae8dc68ea4017a4a14ebc9af592bd060bba3532 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -898,6 +898,13 @@ void RenderThreadImpl::Init(
       base::Bind(&RenderThreadImpl::RecordPurgeAndSuspendMemoryGrowthMetrics,
                  base::Unretained(this)));
 
+  purge_before_suspend_timers_closure_.Reset(base::Bind(
+      &RenderThreadImpl::PurgeBeforeSuspendTimerQueueWhenBackgrounded,
+      base::Unretained(this)));
+  suspend_timers_when_backgrounded_closure_.Reset(
+      base::Bind(&RenderThreadImpl::SuspendTimerQueueWhenBackgrounded,
+                 base::Unretained(this)));

[haraken, 2017/02/03 04:30:49]

Can we call this just before calling PostDelayedTask?

[tasak, 2017/02/03 05:55:26]

Done.

+
   base::MemoryCoordinatorClientRegistry::GetInstance()->Register(this);
 
   // If this renderer doesn't run inside the browser process, enable
@@ -1203,11 +1210,6 @@ void RenderThreadImpl::InitializeWebKit(
     isolate->IsolateInBackgroundNotification();
   }
 
-  renderer_scheduler_->SetTimerQueueSuspensionWhenBackgroundedEnabled(
-      GetContentClient()
-          ->renderer()
-          ->AllowTimerSuspensionWhenProcessBackgrounded());
-
   SkGraphics::SetResourceCacheSingleAllocationByteLimit(
       kImageCacheSingleAllocationByteLimit);
 
@@ -1641,8 +1643,29 @@ 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::PurgeBeforeSuspendTimerQueueWhenBackgrounded,
+        base::Unretained(this)));
+    suspend_timers_when_backgrounded_closure_.Cancel();
+    suspend_timers_when_backgrounded_closure_.Reset(
+        base::Bind(&RenderThreadImpl::SuspendTimerQueueWhenBackgrounded,
+                   base::Unretained(this)));

[haraken, 2017/02/03 04:30:49]

Ditto. Maybe can we Reset the closure just before calling PostDelayedTask?

[tasak, 2017/02/03 05:55:26]

Done.

+
     // TODO(tasak): after enabling MemoryCoordinator, remove this Notify
     // and follow MemoryCoordinator's request.
     if (base::FeatureList::IsEnabled(features::kPurgeAndSuspend))
@@ -1660,6 +1683,32 @@ void RenderThreadImpl::OnProcessBackgrounded(bool backgrounded) {
   }
 }
 
+void RenderThreadImpl::PurgeBeforeSuspendTimerQueueWhenBackgrounded() {
+  DCHECK(IsMainThread());
+  if (!RendererIsHidden())
+    return;
+  // TODO(tasak): use purge method instead of notifying SUSPENDED
+  // when MemoryCoordinator supports.
+  base::MemoryCoordinatorClientRegistry::GetInstance()->Notify(
+      base::MemoryState::SUSPENDED);
+
+  // Since purging is not a synchronous task (e.g. v8 GC, oilpan GC, ...),
+  // we need to wait until the task is finished. So wait 5 seconds and
+  // update purge+suspend UMA histogram.
+  // TODO(tasak): use MemoryCoordinator's callback to report purge+suspend
+  // UMA when MemoryCoordinator is available.
+  GetRendererScheduler()->DefaultTaskRunner()->PostDelayedTask(
+      FROM_HERE, suspend_timers_when_backgrounded_closure_.callback(),
+      base::TimeDelta::FromSeconds(5));
+}
+
+void RenderThreadImpl::SuspendTimerQueueWhenBackgrounded() {
+  DCHECK(IsMainThread());
+  if (!RendererIsHidden())
+    return;
+  renderer_scheduler_->SuspendRenderer();
+}
+
 void RenderThreadImpl::OnProcessPurgeAndSuspend() {
   ChildThreadImpl::OnProcessPurgeAndSuspend();
   if (!RendererIsHidden())