cc: Don't let invalidations that we're going to handle immediately cause an extra commit.

cc/layer.cc

Index: cc/layer.cc
diff --git a/cc/layer.cc b/cc/layer.cc
index b277735fbc083350ccc6c670442f875d344bf5aa..b167edb61f451cfaa931b5f43dab3795280b01a2 100644
--- a/cc/layer.cc
+++ b/cc/layer.cc
@@ -30,6 +30,7 @@ Layer::Layer()
     : m_needsDisplay(false)
     , m_stackingOrderChanged(false)
     , m_layerId(s_nextLayerId++)
+    , m_ignoreSetNeedsCommit(false)
     , m_parent(0)
     , m_layerTreeHost(0)
     , m_layerAnimationController(LayerAnimationController::create(this))
@@ -99,6 +100,8 @@ void Layer::setLayerTreeHost(LayerTreeHost* host)
 
 void Layer::setNeedsCommit()
 {
+    if (m_ignoreSetNeedsCommit)
+        return;
     if (m_layerTreeHost)
         m_layerTreeHost->setNeedsCommit();
 }
@@ -654,7 +657,8 @@ void Layer::setRasterScale(float scale)
         return;
     m_rasterScale = scale;
 
-    if (!m_automaticallyComputeRasterScale)
+    // When automatically computed, this acts like a draw property.
+    if (m_automaticallyComputeRasterScale)
         return;
     setNeedsDisplay();
 }