Extensions: Prepare switch to new permission message system

chrome/common/extensions/permissions/chrome_permission_message_provider.h

Index: chrome/common/extensions/permissions/chrome_permission_message_provider.h
diff --git a/chrome/common/extensions/permissions/chrome_permission_message_provider.h b/chrome/common/extensions/permissions/chrome_permission_message_provider.h
index 068d8bd295a660d9cd9a2ac7f387cf6a2959c0ad..b4f6a8f21e5457c2130268b127b511ca01cc97e9 100644
--- a/chrome/common/extensions/permissions/chrome_permission_message_provider.h
+++ b/chrome/common/extensions/permissions/chrome_permission_message_provider.h
@@ -26,15 +26,18 @@ class ChromePermissionMessageProvider : public PermissionMessageProvider {
   ~ChromePermissionMessageProvider() override;
 
   // PermissionMessageProvider implementation.

[Yoyo Zhou, 2015/03/12 20:55:57]

Add some comments here about the legacy-ness of various methods here. If someone
wants to add some new code using permissions, how do they know what interface to
use, while we have both the old and new systems?

(Even though your next CL will probably be to switch to using the intermediate
state, it'll help to have documentation here.)

[Marc Treib, 2015/03/13 10:43:09]

There are already comments to that effect in permission_message_provider.h. I've
added a pointer to those and a short tl;dr here.

[Yoyo Zhou, 2015/03/13 18:08:13]

Ah, sorry; don't know how I missed that.

-  PermissionMessages GetPermissionMessages(
+  PermissionMessageStrings GetPermissionMessageStrings(
+      const PermissionSet* permissions,
+      Manifest::Type extension_type) const override;
+  PermissionMessageIDs GetLegacyPermissionMessageIDs(
       const PermissionSet* permissions,
       Manifest::Type extension_type) const override;
   CoalescedPermissionMessages GetCoalescedPermissionMessages(
       const PermissionIDSet& permissions) const override;
-  std::vector<base::string16> GetWarningMessages(
+  std::vector<base::string16> GetLegacyWarningMessages(
       const PermissionSet* permissions,
       Manifest::Type extension_type) const override;
-  std::vector<base::string16> GetWarningMessagesDetails(
+  std::vector<base::string16> GetLegacyWarningMessagesDetails(
       const PermissionSet* permissions,
       Manifest::Type extension_type) const override;
   bool IsPrivilegeIncrease(const PermissionSet* old_permissions,
@@ -45,6 +48,10 @@ class ChromePermissionMessageProvider : public PermissionMessageProvider {
       Manifest::Type extension_type) const override;
 
  private:
+  // TODO(treib): Remove this once we've switched to the new system.
+  PermissionMessages GetPermissionMessages(const PermissionSet* permissions,
+                                           Manifest::Type extension_type) const;
+
   // Gets the permission messages for the API permissions. Also adds any
   // permission IDs from API Permissions to |permission_ids|.
   // TODO(sashab): Deprecate the |permissions| argument, and rename this to