From 92886562bf28fff19b8b705f2031da93398644b8 Mon Sep 17 00:00:00 2001
From: Benoit Girard <b56girard@gmail.com>
Date: Mon, 6 Feb 2012 13:51:33 -0500
Subject: [PATCH] Limit composition to every 15 ms, may want to try increasing
 this value

---
 gfx/layers/ipc/CompositorParent.cpp | 10 ++++++++--
 gfx/layers/ipc/CompositorParent.h   |  1 +
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/gfx/layers/ipc/CompositorParent.cpp b/gfx/layers/ipc/CompositorParent.cpp
index b240465ead48..1a9e90d18c2b 100644
--- a/gfx/layers/ipc/CompositorParent.cpp
+++ b/gfx/layers/ipc/CompositorParent.cpp
@@ -132,9 +132,15 @@ CompositorParent::ScheduleComposition()
     return;
   }
 
+  TimeDuration delta = mozilla::TimeStamp::Now() - mLastCompose;
+
   printf_stderr("Schedule composition\n");
   mCurrentCompositeTask = NewRunnableMethod(this, &CompositorParent::Composite);
-  MessageLoop::current()->PostTask(FROM_HERE, mCurrentCompositeTask);
+  if (delta.ToMilliseconds() < 15) {
+    MessageLoop::current()->PostDelayedTask(FROM_HERE, mCurrentCompositeTask, 15 - delta.ToMilliseconds());
+  } else {
+    MessageLoop::current()->PostTask(FROM_HERE, mCurrentCompositeTask);
+  }
 
 // Test code for async scrolling.
 #ifdef OMTC_TEST_ASYNC_SCROLLING
@@ -177,8 +183,8 @@ CompositorParent::Composite()
   Layer* root = mLayerManager->GetRoot();
   root->AsShadowLayer()->SetShadowTransform(worldTransform);
 
-
   mLayerManager->EndEmptyTransaction();
+  mLastCompose = mozilla::TimeStamp::Now();
 }
 
 // Go down shadow layer tree, setting properties to match their non-shadow
diff --git a/gfx/layers/ipc/CompositorParent.h b/gfx/layers/ipc/CompositorParent.h
index cd114c2d66f8..27b28a9a5182 100644
--- a/gfx/layers/ipc/CompositorParent.h
+++ b/gfx/layers/ipc/CompositorParent.h
@@ -131,6 +131,7 @@ private:
   nsRefPtr<LayerManager> mLayerManager;
   nsIWidget* mWidget;
   CancelableTask *mCurrentCompositeTask;
+  TimeStamp mLastCompose;
 
   bool mPaused;
   float mXScale;