Cache GAIA profile picture URL

chrome/browser/profiles/profile_downloader_delegate.h

Index: chrome/browser/profiles/profile_downloader_delegate.h
diff --git a/chrome/browser/profiles/profile_downloader_delegate.h b/chrome/browser/profiles/profile_downloader_delegate.h
index 3a92940a392be6fcf1b71b14dc218bec53ca3241..4dd60c8c27b8032abeb0ff1c56803de96a155dbe 100644
--- a/chrome/browser/profiles/profile_downloader_delegate.h
+++ b/chrome/browser/profiles/profile_downloader_delegate.h
@@ -22,14 +22,19 @@ class ProfileDownloaderDelegate {
 
   // Returns the desired side length of the profile image. If 0, returns image
   // of the originally uploaded size.
-  virtual int GetDesiredImageSideLength() = 0;
+  virtual int GetDesiredImageSideLength() const = 0;
+
+  // Returns the cached URL. If the cache URL matches the new image URL
+  // the image will not be downloaded. Return an empty string when there is no
+  // cached URL.
+  virtual std::string GetCachedPictureURL() const = 0;
 
   // Returns the browser profile associated with this download request.
   virtual Profile* GetBrowserProfile() = 0;
 
   // Whether we should use an OAuth refresh token or the Picasa token from
   // ClientLogin. The latter is currently used in ChromeOS.
-  virtual bool ShouldUseOAuthRefreshToken() = 0;
+  virtual bool ShouldUseOAuthRefreshToken() const = 0;
 
   // Called when the download is complete. On success delegate should query
   // the downloader for values.