Remove Notification::small_image_url_ as it has no users.

Also removes two methods from Notification which only forward calls
to the delegate, and have a single call-site.

BUG=

Review URL: https://codereview.chromium.org/574273003

Cr-Commit-Position: refs/heads/master@{#295499}

chrome/browser/notifications/message_center_notification_manager.cc

@@ -408,7 +408,7 @@ void MessageCenterNotificationManager::ImageDownloads::StartDownloadWithImage(
   if (url.is_empty())
     return;
 
-  content::WebContents* contents = notification.GetWebContents();
+  content::WebContents* contents = notification.delegate()->GetWebContents();
   if (!contents) {
     LOG(WARNING) << "Notification needs an image but has no WebContents";
     return;
@@ -479,7 +479,7 @@ void MessageCenterNotificationManager::ProfileNotification::StartDownloads() {
 
 void
 MessageCenterNotificationManager::ProfileNotification::OnDownloadsCompleted() {
-  notification_.DoneRendering();
+  notification_.delegate()->ReleaseRenderViewHost();
 }
 
 void

chrome/browser/notifications/notification.h

@@ -74,11 +74,6 @@ class Notification : public message_center::Notification {
   // Id of the delegate embedded inside this instance.
   std::string delegate_id() const { return delegate()->id(); }
 
-  content::WebContents* GetWebContents() const {
-    return delegate()->GetWebContents();
-  }
-  void DoneRendering() { delegate()->ReleaseRenderViewHost(); }
-
   NotificationDelegate* delegate() const { return delegate_.get(); }
 
  private:
@@ -96,9 +91,6 @@ class Notification : public message_center::Notification {
   // The URL of a large image to be displayed for a a rich notification.
   GURL image_url_;
 
-  // The URL of a small image to be displayed for a a rich notification.
-  GURL small_image_url_;
-
   // The user-supplied replace ID for the notification.
   base::string16 replace_id_;