Add Observer in FaviconTabHelper

chrome/browser/favicon/favicon_handler_unittest.cc

Index: chrome/browser/favicon/favicon_handler_unittest.cc
diff --git a/chrome/browser/favicon/favicon_handler_unittest.cc b/chrome/browser/favicon/favicon_handler_unittest.cc
index bc5c27da52cff11e4523e441d7a4b124aaa0efe9..57a43922a6f76a12c05a57111c2532820a6288db 100644
--- a/chrome/browser/favicon/favicon_handler_unittest.cc
+++ b/chrome/browser/favicon/favicon_handler_unittest.cc
@@ -227,11 +227,20 @@ class TestFaviconDriver : public FaviconDriver {
 
   void SetActiveURL(GURL url) { url_ = url; }
 
+  void OnFaviconAvailable(const gfx::Image& image) {
+    available_image_ = image;
+  }
+
+  const gfx::Image GetAvailableImage() {
+    return available_image_;
+  }
+
  private:
   GURL favicon_url_;
   GURL url_;
   gfx::Image image_;
   bool favicon_validity_;
+  gfx::Image available_image_;
   DISALLOW_COPY_AND_ASSIGN(TestFaviconDriver);
 };