cc: Add strict layer property change checking and handle bounds changes during paint.

cc/trees/layer_tree_host_common.cc

Index: cc/trees/layer_tree_host_common.cc
diff --git a/cc/trees/layer_tree_host_common.cc b/cc/trees/layer_tree_host_common.cc
index aa9ad5e57255c40ffad3c20b50bf134c9416d9cb..a0bc6cc4d232a323ab27ce63ecef3489d50f1d7e 100644
--- a/cc/trees/layer_tree_host_common.cc
+++ b/cc/trees/layer_tree_host_common.cc
@@ -268,6 +268,17 @@ static inline void UpdateTilePrioritiesForLayer(LayerImpl* layer) {
 
 static inline void UpdateTilePrioritiesForLayer(Layer* layer) {}
 
+static inline void PrepareToUpdateLayer(LayerImpl* layer) {}
+
+static inline void PrepareToUpdateLayer(Layer* layer) {
+  layer->PrepareToUpdate();
+
+  if (layer->mask_layer())
+    layer->mask_layer()->PrepareToUpdate();
+  if (layer->replica_layer() && layer->replica_layer()->mask_layer())
+    layer->replica_layer()->mask_layer()->PrepareToUpdate();
+}
+
 template <typename LayerType>
 static bool SubtreeShouldRenderToSeparateSurface(
     LayerType* layer,
@@ -767,7 +778,8 @@ static void CalculateDrawPropertiesInternal(
     float page_scale_factor,
     bool subtree_can_use_lcd_text,
     gfx::Rect* drawable_content_rect_of_subtree,
-    bool update_tile_priorities) {
+    bool update_tile_priorities,
+    bool prepare_to_update) {
   // This function computes the new matrix transformations recursively for this
   // layer and all its descendants. It also computes the appropriate render
   // surfaces.
@@ -1246,7 +1258,8 @@ static void CalculateDrawPropertiesInternal(
         page_scale_factor,
         subtree_can_use_lcd_text,
         &drawable_content_rect_of_child_subtree,
-        update_tile_priorities);
+        update_tile_priorities,
+        prepare_to_update);
     if (!drawable_content_rect_of_child_subtree.IsEmpty()) {
       accumulated_drawable_content_rect_of_children.Union(
           drawable_content_rect_of_child_subtree);
@@ -1409,6 +1422,9 @@ static void CalculateDrawPropertiesInternal(
     layer->render_target()->render_surface()->
         AddContributingDelegatedRenderPassLayer(layer);
   }
+
+  if (prepare_to_update)
+    PrepareToUpdateLayer(layer);
 }
 
 void LayerTreeHostCommon::CalculateDrawProperties(
@@ -1430,6 +1446,7 @@ void LayerTreeHostCommon::CalculateDrawProperties(
   bool subtree_should_be_clipped = true;
   gfx::Rect device_viewport_rect(device_viewport_size);
   bool update_tile_priorities = false;
+  bool prepare_to_update = true;
 
   // This function should have received a root layer.
   DCHECK(IsRootLayer(root_layer));
@@ -1454,7 +1471,8 @@ void LayerTreeHostCommon::CalculateDrawProperties(
                                                  page_scale_factor,
                                                  can_use_lcd_text,
                                                  &total_drawable_content_rect,
-                                                 update_tile_priorities);
+                                                 update_tile_priorities,
+                                                 prepare_to_update);
 
   // The dummy layer list should not have been used.
   DCHECK_EQ(0u, dummy_layer_list.size());
@@ -1483,6 +1501,7 @@ void LayerTreeHostCommon::CalculateDrawProperties(
   // initial clip rect.
   bool subtree_should_be_clipped = true;
   gfx::Rect device_viewport_rect(device_viewport_size);
+  bool prepare_to_update = false;
 
   // This function should have received a root layer.
   DCHECK(IsRootLayer(root_layer));
@@ -1508,7 +1527,8 @@ void LayerTreeHostCommon::CalculateDrawProperties(
       page_scale_factor,
       can_use_lcd_text,
       &total_drawable_content_rect,
-      update_tile_priorities);
+      update_tile_priorities,
+      prepare_to_update);
 
   // The dummy layer list should not have been used.
   DCHECK_EQ(0u, dummy_layer_list.size());