Mark layers that can use LCD text based on layer transform and opacity.

cc/layer.cc

Index: cc/layer.cc
diff --git a/cc/layer.cc b/cc/layer.cc
index f3f9b4d0dab6c04adf7c6b032164eab4eb0c00ce..6113878e31e81f88fb4dada809aa785bbe6c73bd 100644
--- a/cc/layer.cc
+++ b/cc/layer.cc
@@ -48,7 +48,7 @@ Layer::Layer()
     , m_masksToBounds(false)
     , m_contentsOpaque(false)
     , m_doubleSided(true)
-    , m_useLCDText(false)
+    , m_canUseLCDText(false)
     , m_preserves3D(false)
     , m_useParentBackfaceVisibility(false)
     , m_drawCheckerboardForMissingTiles(false)
@@ -76,9 +76,16 @@ Layer::~Layer()
     removeAllChildren();
 }
 
-void Layer::setUseLCDText(bool useLCDText)
+void Layer::setCanUseLCDText(bool useLCDText)
 {
-    m_useLCDText = useLCDText;
+    if (m_canUseLCDText == useLCDText)
+        return;
+
+    if (!canUseLCDTextWillChange())
+        return;
+
+    m_canUseLCDText = useLCDText;
+    canUseLCDTextDidChange();
 }
 
 void Layer::setLayerTreeHost(LayerTreeHost* host)
@@ -113,6 +120,11 @@ void Layer::setNeedsFullTreeSync()
         m_layerTreeHost->setNeedsFullTreeSync();
 }
 
+bool Layer::canUseLCDTextWillChange()
+{
+    return true;
+}
+
 gfx::Rect Layer::layerRectToContentRect(const gfx::RectF& layerRect) const
 {
     gfx::RectF contentRect = gfx::ScaleRect(layerRect, contentsScaleX(), contentsScaleY());
@@ -567,7 +579,7 @@ void Layer::pushPropertiesTo(LayerImpl* layer)
     layer->setFilters(filters());
     layer->setFilter(filter());
     layer->setBackgroundFilters(backgroundFilters());
-    layer->setUseLCDText(m_useLCDText);
+    layer->setCanUseLCDText(m_canUseLCDText);
     layer->setMasksToBounds(m_masksToBounds);
     layer->setScrollable(m_scrollable);
     layer->setShouldScrollOnMainThread(m_shouldScrollOnMainThread);