Send idle notifications to V8 after commit

content/renderer/gpu/render_widget_compositor.cc

Index: content/renderer/gpu/render_widget_compositor.cc
diff --git a/content/renderer/gpu/render_widget_compositor.cc b/content/renderer/gpu/render_widget_compositor.cc
index dc007a2fc87a6b2efc38c64b2966e0f3d81bcda1..385123057f813260a17e2f3cc11c1b7e2be4fdd3 100644
--- a/content/renderer/gpu/render_widget_compositor.cc
+++ b/content/renderer/gpu/render_widget_compositor.cc
@@ -38,6 +38,7 @@
 #include "third_party/WebKit/public/platform/WebCompositeAndReadbackAsyncCallback.h"
 #include "third_party/WebKit/public/platform/WebSelectionBound.h"
 #include "third_party/WebKit/public/platform/WebSize.h"
+#include "third_party/WebKit/public/web/WebKit.h"
 #include "third_party/WebKit/public/web/WebWidget.h"
 #include "ui/gfx/frame_time.h"
 #include "ui/gl/gl_switches.h"
@@ -163,6 +164,9 @@ scoped_ptr<RenderWidgetCompositor> RenderWidgetCompositor::Create(
 
   CommandLine* cmd = CommandLine::ForCurrentProcess();
 
+  if (cmd->HasSwitch(switches::kSendV8IdleNotificationAfterCommit))
+    compositor->send_v8_idle_notification_after_commit_ = true;

[jamesr, 2014/08/25 18:06:26]

touching a private var directly is dodgy. make this a constructor parameter?

[ernstm, 2014/08/25 18:25:11]

I moved the check for the command line flag into the constructor and set the
member there. Is that okay?

+
   cc::LayerTreeSettings settings;
 
   // For web contents, layer transforms should scale up the contents of layers
@@ -412,7 +416,8 @@ RenderWidgetCompositor::RenderWidgetCompositor(RenderWidget* widget,
                                                bool threaded)
     : threaded_(threaded),
       suppress_schedule_composite_(false),
-      widget_(widget) {
+      widget_(widget),
+      send_v8_idle_notification_after_commit_(false) {
 }
 
 RenderWidgetCompositor::~RenderWidgetCompositor() {}
@@ -758,6 +763,8 @@ void RenderWidgetCompositor::DidBeginMainFrame() {
 }
 
 void RenderWidgetCompositor::BeginMainFrame(const cc::BeginFrameArgs& args) {
+  begin_main_frame_time_ = args.frame_time;
+  begin_main_frame_interval_ = args.interval;
   double frame_time = (args.frame_time - base::TimeTicks()).InSecondsF();
   WebBeginFrameArgs web_begin_frame_args = WebBeginFrameArgs(frame_time);
   widget_->webwidget()->beginFrame(web_begin_frame_args);
@@ -786,6 +793,15 @@ void RenderWidgetCompositor::WillCommit() {
 }
 
 void RenderWidgetCompositor::DidCommit() {
+  if (send_v8_idle_notification_after_commit_) {
+    int idle_time_in_ms =
+        std::max(0L, (begin_main_frame_time_ +
+                      begin_main_frame_interval_ -
+                      gfx::FrameTime::Now()).InMilliseconds());
+    if (idle_time_in_ms)
+      blink::mainThreadIsolate()->IdleNotification(idle_time_in_ms);
+  }
+
   widget_->DidCommitCompositorFrame();
   widget_->didBecomeReadyForAdditionalInput();
 }