Make some updates to extension iconography.

chrome/browser/extensions/api/management/chrome_management_api_delegate.h

 // 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_MANAGEMENT_CHROME_MANAGEMENT_API_DELEGATE_H_
 #define CHROME_BROWSER_EXTENSIONS_API_MANAGEMENT_CHROME_MANAGEMENT_API_DELEGATE_H_
 
 #include "base/task/cancelable_task_tracker.h"
 #include "chrome/browser/extensions/extension_install_prompt.h"
 #include "chrome/browser/extensions/extension_uninstall_dialog.h"
@@ skipping 49 matching lines @@
                           const std::string& transient_extension_id,
                           extensions::UninstallReason reason,
                           const base::Closure& deletion_done_callback,
                           base::string16* error) const override;
   void SetLaunchType(content::BrowserContext* context,
                      const std::string& extension_id,
                      extensions::LaunchType launch_type) const override;
   GURL GetIconURL(const extensions::Extension* extension,
                   int icon_size,
                   ExtensionIconSet::MatchType match,
-                  bool grayscale,
-                  bool* exists) const override;
+                  bool grayscale) const override;
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_MANAGEMENT_CHROME_MANAGEMENT_API_DELEGATE_H_