Adds service to get metadata about images to display on NTP background.

Creates a service that uses SimpleURLLoader to asynchronously request
metadata about images from a specified collection, and makes them
available to the Local NTP in a javascript variable.

Bug: 839152
Change-Id: Ifc2d14bd451f02c42542b3cd5a50bef5c50eb0d4
Reviewed-on: https://chromium-review.googlesource.com/1074339
Commit-Queue: Ramya Nagarajan <[email protected]>
Reviewed-by: Ilya Sherman <[email protected]>
Reviewed-by: Marc Treib <[email protected]>
Reviewed-by: Christian Dullweber <[email protected]>
Cr-Commit-Position: refs/heads/master@{#562736}
diff --git a/chrome/browser/search/local_ntp_source.h b/chrome/browser/search/local_ntp_source.h
index 5fe6b67..1705666 100644
--- a/chrome/browser/search/local_ntp_source.h
+++ b/chrome/browser/search/local_ntp_source.h
@@ -89,6 +89,7 @@
 
   // Overridden from NtpBackgroundServiceObserver:
   void OnCollectionInfoAvailable() override;
+  void OnCollectionImagesAvailable() override;
 
   // Overridden from OneGoogleBarServiceObserver:
   void OnOneGoogleBarDataUpdated() override;
@@ -98,7 +99,8 @@
 
   Profile* const profile_;
 
-  std::vector<NtpBackgroundRequest> ntp_background_requests_;
+  std::vector<NtpBackgroundRequest> ntp_background_collections_requests_;
+  std::vector<NtpBackgroundRequest> ntp_background_image_info_requests_;
 
   NtpBackgroundService* ntp_background_service_;