1 files changed, 18 insertions, 8 deletions

diff --git a/google_apis/drive/base_requests.h b/google_apis/drive/base_requests.h
index d7f46ab..2cfddf0 100644
--- a/google_apis/drive/base_requests.h
+++ b/google_apis/drive/base_requests.h
@@ -30,6 +30,8 @@ namespace google_apis {
 class FileResource;
 class RequestSender;
 
+typedef base::Callback<void(DriveApiErrorCode)> PrepareCallback;
+
 // Callback used for requests that the server returns FileResource data
 // formatted into JSON value.
 typedef base::Callback<void(DriveApiErrorCode error,
@@ -140,6 +142,10 @@ class UrlFetchRequestBase : public AuthenticatedRequestInterface,
   explicit UrlFetchRequestBase(RequestSender* sender);
   ~UrlFetchRequestBase() override;
 
+  // Does async initialization for the request. |Start| calls this method so you
+  // don't need to call this before |Start|.
+  virtual void Prepare(const PrepareCallback& callback);
+
   // Gets URL for the request.
   virtual GURL GetURL() const = 0;
 
@@ -200,6 +206,16 @@ class UrlFetchRequestBase : public AuthenticatedRequestInterface,
   base::SequencedTaskRunner* blocking_task_runner() const;
 
  private:
+  // Continues |Start| function after |Prepare|.
+  void StartAfterPrepare(const std::string& access_token,
+                         const std::string& custom_user_agent,
+                         const ReAuthenticateCallback& callback,
+                         DriveApiErrorCode code);
+
+  // Invokes callback with |code| and request to delete the request to
+  // |sender_|.
+  void CompleteRequestWithError(DriveApiErrorCode code);
+
   // URLFetcherDelegate overrides.
   void OnURLFetchComplete(const net::URLFetcher* source) override;
 
@@ -458,12 +474,8 @@ class MultipartUploadRequestBase : public UrlFetchRequestBase {
                              const ProgressCallback& progress_callback);
   ~MultipartUploadRequestBase() override;
 
-  // Overridden from AuthenticatedRequestInterface.
-  void Start(const std::string& access_token,
-             const std::string& custom_user_agent,
-             const ReAuthenticateCallback& callback) override;
-
   // Overridden from UrlFetchRequestBase.
+  void Prepare(const PrepareCallback& callback) override;
   bool GetContentData(std::string* upload_content_type,
                       std::string* upload_content) override;
   void ProcessURLFetchResults(const net::URLFetcher* source) override;
@@ -480,9 +492,7 @@ class MultipartUploadRequestBase : public UrlFetchRequestBase {
  private:
   // Continues to rest part of |Start| method after determining boundary string
   // of multipart/related.
-  void OnPrepareUploadContent(const std::string& access_token,
-                              const std::string& custom_user_agent,
-                              const ReAuthenticateCallback& callback,
+  void OnPrepareUploadContent(const PrepareCallback& callback,
                               std::string* upload_content_type,
                               std::string* upload_content_data,
                               bool result);