[Background Fetch] Cleanup/fix thread safety

content/browser/blob_storage/chrome_blob_storage_context.h

 // Copyright (c) 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 CONTENT_BROWSER_FILEAPI_CHROME_BLOB_STORAGE_CONTEXT_H_
 #define CONTENT_BROWSER_FILEAPI_CHROME_BLOB_STORAGE_CONTEXT_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 32 matching lines @@
 // same instance.
 //
 // All methods, except the ctor, are expected to be called on
 // the IO thread (unless specifically called out in doc comments).
 class CONTENT_EXPORT ChromeBlobStorageContext
     : public base::RefCountedThreadSafe<ChromeBlobStorageContext,
                                         ChromeBlobStorageContextDeleter> {
  public:
   ChromeBlobStorageContext();
 
+  // Unlike the others, this method must be called on the UI thread.

[Peter Beverloo, 2017/07/10 13:13:21]

// Must be called on the UI thread.

(The first bit is implied by the class-level comment.)

[johnme, 2017/07/10 13:41:07]

Done.

   static ChromeBlobStorageContext* GetFor(
       BrowserContext* browser_context);
 
   void InitializeOnIOThread(base::FilePath blob_storage_dir,
                             scoped_refptr<base::TaskRunner> file_task_runner);
 
   storage::BlobStorageContext* context() const { return context_.get(); }
 
   // Returns a NULL scoped_ptr on failure.
   std::unique_ptr<BlobHandle> CreateMemoryBackedBlob(const char* data,
@@ skipping 40 matching lines @@
 // Attempts to create a vector of BlobDataHandles that ensure any blob data
 // associated with |body| isn't cleaned up until the handles are destroyed.
 // Returns false on failure. This is used for POST and PUT requests.
 bool GetBodyBlobDataHandles(ResourceRequestBody* body,
                             ResourceContext* resource_context,
                             BlobHandles* blob_handles);
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FILEAPI_CHROME_BLOB_STORAGE_CONTEXT_H_