[ImageFetcher] Return http response headers

components/image_fetcher/core/request_metadata.h

Index: components/image_fetcher/core/request_metadata.h
diff --git a/components/image_fetcher/core/request_metadata.h b/components/image_fetcher/core/request_metadata.h
index fbff28c177704a6c875386b1c7a739dcde13d0a0..f625c8294d84d306a0bb39a23cc6cf0574e974df 100644
--- a/components/image_fetcher/core/request_metadata.h
+++ b/components/image_fetcher/core/request_metadata.h
@@ -24,6 +24,12 @@ struct RequestMetadata {
   std::string mime_type;
   int http_response_code;
   bool from_http_cache;
+
+  // Is guaranteed to be a valid pointer only when the callback is called. The
+  // headers may get deleted right after the callback finishes.
+  // TODO(jkrcal): Remove |mime_type| and |http_response_code| as it all can be
+  // read from HttpResponseHeaders.
+  net::HttpResponseHeaders* http_response_headers;
 };
 
 bool operator==(const RequestMetadata& lhs, const RequestMetadata& rhs);