Support different formats in the same resource pool.

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 9d9b247bac466539b3ea5a5e423bda8b82427725..57946ca72b0c5a27d16ce8cd982d805aab00a235 100644
--- a/cc/resources/resource_provider.cc
+++ b/cc/resources/resource_provider.cc
@@ -458,6 +458,11 @@ ResourceProvider::~ResourceProvider() {
   CleanUpGLIfNeeded();
 }
 
+ResourceFormat ResourceProvider::memory_efficient_texture_format(
+    ResourceFormatUsage usage) const {
+  return use_rgba_4444_texture_format_ ? RGBA_4444 : best_texture_format_;
+}
+
 bool ResourceProvider::InUseByConsumer(ResourceId id) {
   Resource* resource = GetResource(id);
   return resource->lock_for_read_count > 0 || resource->exported_count > 0 ||