aura: Allow delegated frames to be used by more than one impl layer.

cc/resources/resource_provider.cc

Index: cc/resources/resource_provider.cc
diff --git a/cc/resources/resource_provider.cc b/cc/resources/resource_provider.cc
index 3d4554c5e2bd3d518f48436045c2eba1262dc8fc..fbc577f663b49c38c3554dea6842d492312ed112 100644
--- a/cc/resources/resource_provider.cc
+++ b/cc/resources/resource_provider.cc
@@ -1479,6 +1479,11 @@ GLint ResourceProvider::WrapModeForTesting(ResourceId id) {
   return resource->wrap_mode;
 }
 
+GLenum ResourceProvider::TargetForTesting(ResourceId id) {
+  Resource* resource = GetResource(id);
+  return resource->target;
+}
+
 void ResourceProvider::LazyCreate(Resource* resource) {
   if (resource->type != GLTexture || resource->gl_id != 0)
     return;