Use flat_set for ResourceIdSet

cc/resources/resource_provider.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_RESOURCES_RESOURCE_PROVIDER_H_
 #define CC_RESOURCES_RESOURCE_PROVIDER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 601 matching lines @@
     const TextureMailbox& mailbox() const { return mailbox_; }
     void set_mailbox(const TextureMailbox& mailbox);
 
     void SetLocallyUsed();
     void SetSynchronized();
     void UpdateSyncToken(const gpu::SyncToken& sync_token);
     int8_t* GetSyncTokenData();
     void WaitSyncToken(gpu::gles2::GLES2Interface* gl);
 
     int child_id;
+    ResourceId id_in_child;
     unsigned gl_id;
     // Pixel buffer used for set pixels without unnecessary copying.
     unsigned gl_pixel_buffer_id;
     // Query used to determine when asynchronous set pixels complete.
     unsigned gl_upload_query_id;
     // Query used to determine when read lock fence has passed.
     unsigned gl_read_lock_query_id;
     ReleaseCallbackImpl release_callback_impl;
     uint8_t* pixels;
     int lock_for_read_count;
@@ skipping 57 matching lines @@
     DISALLOW_COPY_AND_ASSIGN(Resource);
   };
   using ResourceMap = std::unordered_map<ResourceId, Resource>;
 
   struct Child {
     Child();
     Child(const Child& other);
     ~Child();
 
     ResourceIdMap child_to_parent_map;
-    ResourceIdMap parent_to_child_map;
     ReturnCallback return_callback;
     bool marked_for_deletion;
     bool needs_sync_tokens;
   };
   using ChildMap = std::unordered_map<int, Child>;
 
   bool ReadLockFenceHasPassed(const Resource* resource) {
     return !resource->read_lock_fence.get() ||
            resource->read_lock_fence->HasPassed();
   }
@@ skipping 102 matching lines @@
   // Set of resource Ids that would like to be notified about promotion hints.
   ResourceIdSet wants_promotion_hints_set_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(ResourceProvider);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_RESOURCE_PROVIDER_H_