net: Allow URLFetcher users to inject custom URLFetcherResponseWriter

net/url_request/url_fetcher.h

Index: net/url_request/url_fetcher.h
diff --git a/net/url_request/url_fetcher.h b/net/url_request/url_fetcher.h
index d888fbfd240bd108aa92effd337aea9d23bc8d9a..1de8bad0872b71e3c4b6b07199dd15df3d008bb7 100644
--- a/net/url_request/url_fetcher.h
+++ b/net/url_request/url_fetcher.h
@@ -10,6 +10,7 @@
 
 #include "base/callback_forward.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/supports_user_data.h"
 #include "base/task_runner.h"
 #include "net/base/net_export.h"
@@ -27,6 +28,7 @@ class HostPortPair;
 class HttpRequestHeaders;
 class HttpResponseHeaders;
 class URLFetcherDelegate;
+class URLFetcherResponseWriter;
 class URLRequestContextGetter;
 class URLRequestStatus;
 typedef std::vector<std::string> ResponseCookies;
@@ -239,6 +241,11 @@ class NET_EXPORT URLFetcher {
   virtual void SaveResponseToTemporaryFile(
       scoped_refptr<base::TaskRunner> file_task_runner) = 0;
 
+  // By default, the response is saved in a string. Call this method to use the
+  // specified writer to save the response. Must be called before Start().
+  virtual void SaveResponseWithWriter(
+      scoped_ptr<URLFetcherResponseWriter> response_writer) = 0;

[wtc, 2013/10/14 19:57:23]

Why don't you remove the SaveResponseToFileAtPath and
SaveResponseToTemporaryFile methods? Are you planning to remove them later?

[hashimoto, 2013/10/15 01:00:35]

I thought it might be OK to leave SaveResponseToFileAtPath,
SaveResponseToTemporaryFile and GetResponseAsFilePath unremoved because these
methods are quite simple now.
But if we are to remove these methods, we can do it later, after converting all
user code (Google Drive, imageburner, component_updater and extension_download)
to use SaveResponseWithWriter.

+
   // Retrieve the response headers from the request.  Must only be called after
   // the OnURLFetchComplete callback has run.
   virtual HttpResponseHeaders* GetResponseHeaders() const = 0;