Purge memory via MemoryCoordinatorClientRegistry when a backgrounded renderer is suspended.

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 7296ab1965a7c5116af4244b3ebf7c479521b458..531e31bcff7a9b05244fd4d569bea0eb6d97cfff 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -846,7 +846,8 @@ void RenderThreadImpl::Init(
       base::Bind(&RenderThreadImpl::OnSyncMemoryPressure,
                  base::Unretained(this))));
 
-  if (base::FeatureList::IsEnabled(features::kMemoryCoordinator)) {
+  if (base::FeatureList::IsEnabled(features::kMemoryCoordinator) ||
+      base::FeatureList::IsEnabled(features::kPurgeAndSuspend)) {

[bashi, 2016/10/28 05:45:05]

Let's discuss offline how to enable MemoryCoordinatorClients for purge+suspend
experiment. I think that enabling ChildMemoryCoordinator without enabling
MemoryCoordinator in browser side may break many things.

[tasak, 2016/10/28 06:29:34]

According to the discussion, I removed
base::FeatureList::IsEnabled(kPurgeAndSuspend), because
MemoryCoordinatorClientRegistry::Notify works without MemoryCoordinator.
Instead, I added DCHECK(!base::FeatuerList::IsEnabled(kPurgeAndSuspsned) inside
the "if".

     // Disable MemoryPressureListener when memory coordinator is enabled.
     base::MemoryPressureListener::SetNotificationsSuppressed(true);
 
@@ -1756,6 +1757,12 @@ void RenderThreadImpl::OnProcessBackgrounded(bool backgrounded) {
     renderer_scheduler_->OnRendererBackgrounded();
   } else {
     renderer_scheduler_->OnRendererForegrounded();
+    // TODO(tasak): after enabling MemoryCoordinator, remove this Notify
+    // and follow MemoryCoordinator's request.
+    if (base::FeatureList::IsEnabled(features::kPurgeAndSuspend))
+      base::MemoryCoordinatorClientRegistry::GetInstance()->Notify(
+          base::MemoryState::NORMAL);
+
     record_purge_suspend_metric_closure_.Cancel();
     record_purge_suspend_metric_closure_.Reset(
         base::Bind(&RenderThreadImpl::RecordPurgeAndSuspendMetrics,
@@ -1766,11 +1773,17 @@ void RenderThreadImpl::OnProcessBackgrounded(bool backgrounded) {
 
 void RenderThreadImpl::OnProcessPurgeAndSuspend() {
   ChildThreadImpl::OnProcessPurgeAndSuspend();
-  if (is_renderer_suspended_ || !RendererIsHidden())
+  DCHECK(!is_renderer_suspended_);
+  if (!RendererIsHidden())
     return;
-  // TODO(hajimehoshi): Implement purging e.g. cache (crbug/607077)
   is_renderer_suspended_ = true;
-  renderer_scheduler_->SuspendRenderer();
+  if (base::FeatureList::IsEnabled(features::kPurgeAndSuspend)) {
+    // TODO(tasak): After enabling MemoryCoordinator, remove this Notify
+    // and follow MemoryCoordinator's request.
+    base::MemoryCoordinatorClientRegistry::GetInstance()->Notify(
+        base::MemoryState::SUSPENDED);
+    renderer_scheduler_->SuspendRenderer();
+  }
 
   // Since purging is not a synchronous task (e.g. v8 GC, oilpan GC, ...),
   // we need to wait until the task is finished. So wait 15 seconds and
@@ -1882,7 +1895,13 @@ void RenderThreadImpl::OnProcessResume() {
 
   DCHECK(is_renderer_suspended_);
   is_renderer_suspended_ = false;
-  renderer_scheduler_->ResumeRenderer();
+  if (base::FeatureList::IsEnabled(features::kPurgeAndSuspend)) {
+    // TODO(tasak): after enabling MemoryCoordinator, remove this Notify
+    // and follow MemoryCoordinator's request.
+    base::MemoryCoordinatorClientRegistry::GetInstance()->Notify(
+        base::MemoryState::NORMAL);
+    renderer_scheduler_->ResumeRenderer();
+  }
 }
 
 scoped_refptr<gpu::GpuChannelHost> RenderThreadImpl::EstablishGpuChannelSync() {