[Blob] BlobReader class & tests, and removal of all redundant reading.

storage/browser/blob/blob_url_request_job_factory.h

Index: storage/browser/blob/blob_url_request_job_factory.h
diff --git a/storage/browser/blob/blob_url_request_job_factory.h b/storage/browser/blob/blob_url_request_job_factory.h
index 7f7a5506447ad7eb617d9aaa5c11fef9c9a37a1d..e00d41438960713f063abdbbeb4ddc98c6873d5b 100644
--- a/storage/browser/blob/blob_url_request_job_factory.h
+++ b/storage/browser/blob/blob_url_request_job_factory.h
@@ -26,7 +26,6 @@ class URLRequestContext;
 
 namespace storage {
 
-class BlobDataSnapshot;
 class BlobDataHandle;
 class BlobStorageContext;
 
@@ -56,7 +55,7 @@ class STORAGE_EXPORT BlobProtocolHandler
       net::NetworkDelegate* network_delegate) const override;
 
  private:
-  scoped_ptr<BlobDataSnapshot> LookupBlobData(net::URLRequest* request) const;
+  BlobDataHandle* LookupBlobHandle(net::URLRequest* request) const;
 
   base::WeakPtr<BlobStorageContext> context_;
   const scoped_refptr<storage::FileSystemContext> file_system_context_;