Add browser test for CustomizationWallpaperDownloader.

chrome/browser/chromeos/customization_wallpaper_downloader.h

Index: chrome/browser/chromeos/customization_wallpaper_downloader.h
diff --git a/chrome/browser/chromeos/customization_wallpaper_downloader.h b/chrome/browser/chromeos/customization_wallpaper_downloader.h
index 9922ffbdc2b9a43285784a4b985910a767735f09..fb9be1eda3d0904a01689de7d4a08064a0bc3098 100644
--- a/chrome/browser/chromeos/customization_wallpaper_downloader.h
+++ b/chrome/browser/chromeos/customization_wallpaper_downloader.h
@@ -53,6 +53,14 @@ class CustomizationWallpaperDownloader : public net::URLFetcherDelegate {
   virtual void OnURLFetchComplete(const net::URLFetcher* source) OVERRIDE;
 
  private:
+  // This class is used in tests.
+  friend class TestWallpaperImageURLFetcherCallback;
+
+  // This is called in tests to modify (lower) retry delay.
+  void set_retry_delay_for_testing(double value) {

[Daniel Erat, 2014/04/30 21:23:06]

leave this as public; there's a presubmit check that _for_testing methods aren't
called from outside of tests. (you probably don't need to list the friend then,
right?)

also use base::TimeDelta instead of double. "double value" doesn't explain
anything about the units that are being used -- everyone calling this would need
to read the implementation to see what to pass.

[Alexander Alekseev, 2014/05/04 23:30:56]

Done.

+    retry_delay_seconds_ = value;
+  }
+
   // Start new request.
   void StartRequest();
 
@@ -89,6 +97,10 @@ class CustomizationWallpaperDownloader : public net::URLFetcherDelegate {
   // Number of download retries (first attempt is not counted as retry).
   size_t retries_;
 
+  // Sleep between retry requests (increasing, see Retry() method for details).
+  // Non-constant value for tests.
+  double retry_delay_seconds_;

[Daniel Erat, 2014/04/30 21:23:06]

base::TimeDelta

[Alexander Alekseev, 2014/05/04 23:30:56]

Done.

+
   // Callback supplied by caller.
   base::Callback<void(bool success, const GURL&)> on_wallpaper_fetch_completed_;