mix-blend-mode implementation for accelerated layers

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 99f950293ce7da829a371f41af2a36cff9eba440..16ba7e1442c51d8a5eb0f0c517b920fa8b9316a4 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -53,6 +53,8 @@ LayerImpl::LayerImpl(LayerTreeImpl* tree_impl, int id)
       masks_to_bounds_(false),
       contents_opaque_(false),
       opacity_(1.0),
+      blend_mode_(SkXfermode::kSrcOver_Mode),
+      is_root_for_isolated_group_(false),
       preserves_3d_(false),
       use_parent_backface_visibility_(false),
       draw_checkerboard_for_missing_tiles_(false),
@@ -246,7 +248,8 @@ scoped_ptr<SharedQuadState> LayerImpl::CreateSharedQuadState() const {
                 draw_properties_.visible_content_rect,
                 draw_properties_.clip_rect,
                 draw_properties_.is_clipped,
-                draw_properties_.opacity);
+                draw_properties_.opacity,
+                blend_mode_);
   return state.Pass();
 }
 
@@ -524,6 +527,8 @@ void LayerImpl::PushPropertiesTo(LayerImpl* layer) {
   layer->SetTouchEventHandlerRegion(touch_event_handler_region_);
   layer->SetContentsOpaque(contents_opaque_);
   layer->SetOpacity(opacity_);
+  layer->SetBlendMode(blend_mode_);
+  layer->SetIsRootForIsolatedGroup(is_root_for_isolated_group_);
   layer->SetPosition(position_);
   layer->SetIsContainerForFixedPositionLayers(
       is_container_for_fixed_position_layers_);
@@ -880,6 +885,24 @@ bool LayerImpl::OpacityIsAnimatingOnImplOnly() const {
   return opacity_animation && opacity_animation->is_impl_only();
 }
 
+void LayerImpl::SetBlendMode(SkXfermode::Mode blend_mode) {
+  if (blend_mode_ == blend_mode)
+    return;
+
+  blend_mode_ = blend_mode;
+  NoteLayerPropertyChangedForSubtree();
+}
+
+void LayerImpl::SetIsRootForIsolatedGroup(bool root) {
+  if (is_root_for_isolated_group_ == root)
+    return;
+
+  is_root_for_isolated_group_ = root;
+  // Specifying the root for an isolated group does not affect the current
+  // layer; it affects only children.
+  NoteLayerPropertyChangedForDescendants();

[rosca, 2013/11/21 13:04:46]

enne: could you please take another look at this change? Do you think I should
change it to NoteLayerPropertyChangedForSubtree()? When a layer gets isolated it
doesn't change the way it looks. Only descendants having a blend mode can look
different, because they use the backdrop limited to this root.

[enne (OOO), 2013/11/21 18:15:59]

Hmm, on second thought this should be removed.  Making something an isolated
group promotes it to be a render surface, but that shouldn't change the way it
is being rendered.  We don't mark something as changed when we put a copy
request on it.

+}
+
 void LayerImpl::SetPosition(gfx::PointF position) {
   if (position_ == position)
     return;
@@ -1281,6 +1304,9 @@ CompositingReasonsAsValue(CompositingReasons reasons) {
   if (reasons & kCompositingReasonOutOfFlowClipping)
     reason_list->AppendString("Has clipping ancestor");
 
+  if (reasons & kCompositingReasonIsolateCompositedDescendants)
+    reason_list->AppendString("Should isolate composited descendants");
+
   return reason_list.PassAs<base::Value>();
 }