Add recommended extension installation support

chrome/browser/extensions/external_policy_loader.h

 // Copyright (c) 2012 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_EXTERNAL_POLICY_LOADER_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTERNAL_POLICY_LOADER_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "chrome/browser/extensions/extension_management.h"
 #include "chrome/browser/extensions/external_loader.h"
 
 namespace base {
 class DictionaryValue;
 }
 
 namespace extensions {
 
 // A specialization of the ExternalProvider that uses extension management
 // policies to look up which external extensions are registered.
 class ExternalPolicyLoader : public ExternalLoader,
                              public ExtensionManagement::Observer {
  public:
-  explicit ExternalPolicyLoader(ExtensionManagement* settings);
+  // Indicates the policies for installed extensions from this class, according
+  // to management polices.
+  enum InstallationType {
+    // Installed extensions are not allowed to be disabled or removed.
+    FORCED,
+    // Installed extensions are allowed to be disabled but not removed.
+    RECOMMENDED
+  };
+
+  ExternalPolicyLoader(ExtensionManagement* settings, InstallationType type);
 
   // ExtensionManagement::Observer implementation
   virtual void OnExtensionManagementSettingsChanged() override;
 
   // Adds an extension to be updated to the pref dictionary.
   static void AddExtension(base::DictionaryValue* dict,
                            const std::string& extension_id,
                            const std::string& update_url);
 
  protected:
   virtual void StartLoading() override;
 
  private:
   friend class base::RefCountedThreadSafe<ExternalLoader>;
 
   virtual ~ExternalPolicyLoader();
 
   ExtensionManagement* settings_;
+  InstallationType type_;
 
   DISALLOW_COPY_AND_ASSIGN(ExternalPolicyLoader);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTERNAL_POLICY_LOADER_H_