cc: Remove contents_texture_manager from LayerTreeHost(Impl) and proxy.

cc/trees/layer_tree_impl.h

Index: cc/trees/layer_tree_impl.h
diff --git a/cc/trees/layer_tree_impl.h b/cc/trees/layer_tree_impl.h
index fb4440b4cecaf714d32e4641f1b2ddd23f631c9e..e58506e8af38425c55b49b5e47070975144cad76 100644
--- a/cc/trees/layer_tree_impl.h
+++ b/cc/trees/layer_tree_impl.h
@@ -259,10 +259,6 @@ class CC_EXPORT LayerTreeImpl {
 
   void DidBecomeActive();
 
-  bool ContentsTexturesPurged() const;
-  void SetContentsTexturesPurged();
-  void ResetContentsTexturesPurged();
-
   // Set on the active tree when the viewport size recently changed
   // and the active tree's size is now out of date.
   bool ViewportSizeInvalid() const;
@@ -400,7 +396,6 @@ class CC_EXPORT LayerTreeImpl {
   // would not be fully covered by opaque content.
   Region unoccluded_screen_space_region_;
 
-  bool contents_textures_purged_;
   bool viewport_size_invalid_;
   bool needs_update_draw_properties_;