GetAvatarForIdentity now accepts a nil callback function.

Change-Id: I6dedc52a8f0eb4ff4bd0186158485bd15671e89e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1618316
Auto-Submit: Peter Lee <pkl@chromium.org>
Commit-Queue: Jérôme Lebel <jlebel@chromium.org>
Reviewed-by: Jérôme Lebel <jlebel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#661309}

ios/chrome/browser/ui/authentication/signin_confirmation_view_controller.mm

@@ -59,8 +59,7 @@ UIImage* GetImageForIdentity(ChromeIdentity* identity) {
     // (including the corresponding AccountViewBase).
     ios::GetChromeBrowserProvider()
         ->GetChromeIdentityService()
-        ->GetAvatarForIdentity(identity, ^(UIImage*){
-                               });
+        ->GetAvatarForIdentity(identity, nil);
   }
   return image;
 }

ios/chrome/browser/ui/settings/settings_table_view_controller.mm

@@ -1210,8 +1210,7 @@ void IdentityObserverBridge::OnPrimaryAccountCleared(
     // (including the corresponding AccountViewBase).
     ios::GetChromeBrowserProvider()
         ->GetChromeIdentityService()
-        ->GetAvatarForIdentity(_identity, ^(UIImage*){
-                               });
+        ->GetAvatarForIdentity(_identity, nil);
   }
 
   // If the currently used image has already been resized, use it.