Remove offscreen compositor contexts.

cc/layers/layer.cc

Index: cc/layers/layer.cc
diff --git a/cc/layers/layer.cc b/cc/layers/layer.cc
index 733ecd2dbc6d4eca593b8c0fc9a1a1d4e875677d..29c5c8e0b2ad0786d216894206520246d4527c91 100644
--- a/cc/layers/layer.cc
+++ b/cc/layers/layer.cc
@@ -133,7 +133,6 @@ void Layer::SetLayerTreeHost(LayerTreeHost* host) {
 
   if (host && layer_animation_controller_->has_any_animation())
     host->SetNeedsCommit();
-  SetNeedsFilterContextIfNeeded();
 }
 
 void Layer::SetNeedsUpdate() {
@@ -167,15 +166,6 @@ void Layer::SetNextCommitWaitsForActivation() {
   layer_tree_host_->SetNextCommitWaitsForActivation();
 }
 
-void Layer::SetNeedsFilterContextIfNeeded() {
-  if (!layer_tree_host_)
-    return;
-
-  if (!filters_.IsEmpty() || !background_filters_.IsEmpty() ||
-      !uses_default_blend_mode())
-    layer_tree_host_->set_needs_filter_context();
-}
-
 void Layer::SetNeedsPushProperties() {
   if (needs_push_properties_)
     return;
@@ -487,7 +477,6 @@ void Layer::SetFilters(const FilterOperations& filters) {
     return;
   filters_ = filters;
   SetNeedsCommit();
-  SetNeedsFilterContextIfNeeded();
 }
 
 bool Layer::FilterIsAnimating() const {
@@ -500,7 +489,6 @@ void Layer::SetBackgroundFilters(const FilterOperations& filters) {
     return;
   background_filters_ = filters;
   SetNeedsCommit();
-  SetNeedsFilterContextIfNeeded();
 }
 
 void Layer::SetOpacity(float opacity) {
@@ -566,7 +554,6 @@ void Layer::SetBlendMode(SkXfermode::Mode blend_mode) {
 
   blend_mode_ = blend_mode;
   SetNeedsCommit();
-  SetNeedsFilterContextIfNeeded();
 }
 
 void Layer::SetIsRootForIsolatedGroup(bool root) {