[Extensions] Pull ExtensionId into its own file

chrome/browser/extensions/extension_management_test_util.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_EXTENSION_MANAGEMENT_TEST_UTIL_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_MANAGEMENT_TEST_UTIL_H_
 
 #include <memory>
 #include <string>
 
 #include "base/macros.h"
 #include "base/values.h"
 #include "chrome/browser/extensions/extension_management_constants.h"
 #include "extensions/browser/pref_names.h"
-#include "extensions/common/extension.h"
+#include "extensions/common/extension_id.h"
 
 namespace policy {
 class MockConfigurationPolicyProvider;
 class PolicyBundle;
 }  // namespace policy
 
 namespace extensions {
 
 // Base class for essential routines on preference manipulation.
 class ExtensionManagementPrefUpdaterBase {
@@ skipping 115 matching lines @@
  private:
   policy::MockConfigurationPolicyProvider* provider_;
   std::unique_ptr<policy::PolicyBundle> policies_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionManagementPolicyUpdater);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_MANAGEMENT_TEST_UTIL_H_