[BlobAsync] Faster shortcuttin, make renderer controller leaky & alive.

storage/browser/blob/blob_async_builder_host.h

 // Copyright 2015 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 STORAGE_BROWSER_BLOB_BLOB_ASYNC_BUILDER_HOST_H_
 #define STORAGE_BROWSER_BLOB_BLOB_ASYNC_BUILDER_HOST_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 81 matching lines @@
 
   // This is called when we have responses from the Renderer to our calls to
   // the request_memory callback above. See above for return value meaning.
   BlobTransportResult OnMemoryResponses(
       const std::string& uuid,
       const std::vector<BlobItemBytesResponse>& responses,
       BlobStorageContext* context);
 
   // This removes the BlobBuildingState from our map and flags the blob as
   // broken in the context. This can be called both from our own logic to cancel
-  // the blob, or from the DispatcherHost (Renderer). If the blob isn't being
-  // built then we do nothing.
+  // the blob, or from the DispatcherHost (Renderer). The blob MUST be being
+  // built in this builder.
   // Note: if the blob isn't in the context (renderer dereferenced it before we
   // finished constructing), then we don't bother touching the context.
   void CancelBuildingBlob(const std::string& uuid,
                           IPCBlobCreationCancelCode code,
                           BlobStorageContext* context);
 
   // This clears this object of pending construction. It also handles marking
   // blobs that haven't been fully constructed as broken in the context if there
   // are any references being held by anyone.
   void CancelAll(BlobStorageContext* context);
 
+  bool IsEmpty() const { return async_blob_map_.empty(); }
+
   size_t blob_building_count() const { return async_blob_map_.size(); }
 
   bool IsBeingBuilt(const std::string& key) const {
     return async_blob_map_.find(key) != async_blob_map_.end();
   }
 
   // For testing use only.  Must be called before StartBuildingBlob.
   void SetMemoryConstantsForTesting(size_t max_ipc_memory_size,
                                     size_t max_shared_memory_size,
                                     uint64_t max_file_size) {
@@ skipping 67 matching lines @@
   size_t max_shared_memory_size_ = kBlobStorageMaxSharedMemoryBytes;
   uint64_t max_file_size_ = kBlobStorageMaxFileSizeBytes;
 
   base::WeakPtrFactory<BlobAsyncBuilderHost> ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BlobAsyncBuilderHost);
 };
 
 }  // namespace storage
 #endif  // STORAGE_BROWSER_BLOB_BLOB_ASYNC_BUILDER_HOST_H_