Add content pack information to Extension.

chrome/common/extensions/extension_manifest_constants.h

Index: chrome/common/extensions/extension_manifest_constants.h
diff --git a/chrome/common/extensions/extension_manifest_constants.h b/chrome/common/extensions/extension_manifest_constants.h
index 28310223c86d2379e5f4b1d2ab43d588cc1865ff..fe24acc4ecbfc3e5fd006b87d1ec93e3800af31b 100644
--- a/chrome/common/extensions/extension_manifest_constants.h
+++ b/chrome/common/extensions/extension_manifest_constants.h
@@ -24,6 +24,8 @@ namespace extension_manifest_keys {
   extern const char kBrowseURLs[];
   extern const char kChromeURLOverrides[];
   extern const char kCommands[];
+  extern const char kContentPack[];
+  extern const char kContentPackSites[];
   extern const char kContentScripts[];
   extern const char kContentSecurityPolicy[];
   extern const char kConvertedFromUserScript[];
@@ -189,6 +191,8 @@ namespace extension_manifest_errors {
   extern const char kInvalidBrowseURLs[];
   extern const char kInvalidChromeURLOverrides[];
   extern const char kInvalidCommandsKey[];
+  extern const char kInvalidContentPack[];
+  extern const char kInvalidContentPackSites[];
   extern const char kInvalidContentScript[];
   extern const char kInvalidContentScriptsList[];
   extern const char kInvalidContentSecurityPolicy[];