cc: Add support for partial swaps when using impl-side painting.

cc/layers/layer_impl.cc

Index: cc/layers/layer_impl.cc
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index 135a6163c0c9489e99387f7d0fbde13d2b2e8b4c..4a2ced0c83e659309e0236c199eb6a855c1a73a6 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -71,7 +71,8 @@ LayerImpl::LayerImpl(LayerTreeImpl* tree_impl, int id)
       draw_depth_(0.f),
       needs_push_properties_(false),
       num_dependents_need_push_properties_(0),
-      current_draw_mode_(DRAW_MODE_NONE) {
+      current_draw_mode_(DRAW_MODE_NONE),
+      initialized_tile_rect_(gfx::Rect()) {

[reveman, 2014/04/11 18:11:34]

no need for this. default ctor does the same.

[sohanjg, 2014/04/14 10:16:11]

Done.

   DCHECK_GT(layer_id_, 0);
   DCHECK(layer_tree_impl_);
   layer_tree_impl_->RegisterLayer(this);
@@ -1017,6 +1018,13 @@ void LayerImpl::SetUpdateRect(const gfx::RectF& update_rect) {
   SetNeedsPushProperties();
 }
 
+void LayerImpl::SetInitializedTileRect(gfx::Rect initialized_tile_rect) {

[reveman, 2014/04/11 18:11:34]

pass by const reference instead

+  if (!this)

[reveman, 2014/04/11 18:11:34]

heh, nope.

[sohanjg, 2014/04/14 10:16:11]

Done.

+    return;
+  initialized_tile_rect_ =
+      gfx::UnionRects(initialized_tile_rect_, initialized_tile_rect);

[reveman, 2014/04/11 18:11:34]

don't call this function "SetRect" and then do a union.

[sohanjg, 2014/04/14 10:16:11]

Done.

+}
+
 void LayerImpl::SetContentBounds(const gfx::Size& content_bounds) {
   if (this->content_bounds() == content_bounds)
     return;