Handle app custom icon via aura::Window property.

extensions/shell/browser/shell_app_delegate.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/shell/browser/shell_app_delegate.h"
 
 #include "content/public/browser/web_contents.h"
 #include "extensions/common/constants.h"
 #include "extensions/shell/browser/media_capture_util.h"
 #include "extensions/shell/browser/shell_extension_web_contents_observer.h"
@@ skipping 63 matching lines @@
 
 bool ShellAppDelegate::CheckMediaAccessPermission(
     content::WebContents* web_contents,
     const GURL& security_origin,
     content::MediaStreamType type,
     const Extension* extension) {
   media_capture_util::VerifyMediaAccessPermission(type, extension);
   return true;
 }
 
-int ShellAppDelegate::PreferredIconSize() {
+int ShellAppDelegate::PreferredIconSize() const {
   return extension_misc::EXTENSION_ICON_SMALL;
 }
 
 void ShellAppDelegate::SetWebContentsBlocked(
     content::WebContents* web_contents,
     bool blocked) {
   NOTIMPLEMENTED();
 }
 
 bool ShellAppDelegate::IsWebContentsVisible(
     content::WebContents* web_contents) {
   return true;
 }
 
 void ShellAppDelegate::SetTerminatingCallback(const base::Closure& callback) {
   // TODO(jamescook): Should app_shell continue to close the app window
   // manually or should it use a browser termination callback like Chrome?
 }
 
 }  // namespace extensions