Move permission warning message handling from PermissionSet to PermissionMessageProvider.

extensions/common/permissions/permission_message_provider.h

+// Copyright 2013 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 EXTENSIONS_COMMON_PERMISSIONS_PERMISSION_MESSAGE_PROVIDER_H_
+#define EXTENSIONS_COMMON_PERMISSIONS_PERMISSION_MESSAGE_PROVIDER_H_
+
+#include <vector>
+
+#include "extensions/common/manifest.h"
+#include "extensions/common/permissions/permission_message.h"
+
+namespace extensions {
+
+class PermissionSet;
+
+// The PermissionMessageProvider interprets permissions, translating them
+// into warning messages to show to the user. It also determines whether
+// a new set of permissions entails showing new warning messages.
+class PermissionMessageProvider {
+ public:
+  PermissionMessageProvider() {}
+  virtual ~PermissionMessageProvider() {}
+
+  // Return the registered permission message provider for the extension type.
+  static PermissionMessageProvider* Get(Manifest::Type extension_type);
+
+  // Set the permissions providers for Get() to return. |default_provider|
+  // is returned for types, unless a custom provider is given with that type
+  // in |custom_providers|. Takes ownership of the given providers.
+  static void SetProviders(

[Matt Perry, 2013/10/16 20:07:04]

This interface feels a bit clunky. How about splitting it up into:
  SetDefaultProvider(x);
  SetProviderForType(type, x);

Also, use scoped_ptr to advertise the ownership transfer.

[Yoyo Zhou, 2013/10/17 19:45:52]

I moved the ownership to ChromeExtensionsClient.

+      PermissionMessageProvider* default_provider,
+      const std::vector<std::pair<Manifest::Type, PermissionMessageProvider*> >&
+          custom_providers);
+
+  // Gets the localized permission messages that represent this set.
+  // The set of permission messages shown varies by extension type.
+  virtual PermissionMessages GetPermissionMessages(
+      const PermissionSet* permissions) const = 0;
+
+  // Gets the localized permission messages that represent this set (represented
+  // as strings). The set of permission messages shown varies by extension type.
+  virtual std::vector<string16> GetWarningMessages(
+      const PermissionSet* permissions) const = 0;
+
+  // Gets the localized permission details for messages that represent this set
+  // (represented as strings). The set of permission messages shown varies by
+  // extension type.
+  virtual std::vector<string16> GetWarningMessagesDetails(
+      const PermissionSet* permissions) const = 0;
+
+  // Returns true if |new_permissions| has a greater privilege level than
+  // |old_permissions|.
+  // Whether certain permissions are considered varies by extension type.
+  virtual bool IsPrivilegeIncrease(
+      const PermissionSet* old_permissions,
+      const PermissionSet* new_permissions) const = 0;
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_COMMON_PERMISSIONS_PERMISSION_MESSAGE_PROVIDER_H_