components/image_fetcher: Expose RequestMetadata from ImageFetcher

components/image_fetcher/image_fetcher.h

Index: components/image_fetcher/image_fetcher.h
diff --git a/components/image_fetcher/image_fetcher.h b/components/image_fetcher/image_fetcher.h
index a5b1c7f1d7575845c70ac677c6f97ef508d24df6..0fe7ea4802a81b950feeba719e6bd6c60fced7b2 100644
--- a/components/image_fetcher/image_fetcher.h
+++ b/components/image_fetcher/image_fetcher.h
@@ -22,6 +22,8 @@ namespace image_fetcher {
 
 class ImageDecoder;
 
+struct RequestMetadata;
+
 // A class used to fetch server images. It can be called from any thread and the
 // callback will be called on the thread which initiated the fetch.
 class ImageFetcher {
@@ -29,6 +31,11 @@ class ImageFetcher {
   ImageFetcher() {}
   virtual ~ImageFetcher() {}
 
+  using ImageFetcherCallback =
+      base::Callback<void(const std::string& id,
+                          const gfx::Image& image,
+                          const RequestMetadata& metadata)>;

[jkrcal, 2017/03/20 10:49:59]

A nice cleanup!

+
   using DataUseServiceName = data_use_measurement::DataUseUserData::ServiceName;
 
   virtual void SetImageFetcherDelegate(ImageFetcherDelegate* delegate) = 0;
@@ -50,7 +57,7 @@ class ImageFetcher {
   virtual void StartOrQueueNetworkRequest(
       const std::string& id,
       const GURL& image_url,
-      base::Callback<void(const std::string&, const gfx::Image&)> callback) = 0;
+      const ImageFetcherCallback& callback) = 0;
 
   virtual ImageDecoder* GetImageDecoder() = 0;