Move Extension into extensions namespace

chrome/common/extensions/extension.h

Index: chrome/common/extensions/extension.h
diff --git a/chrome/common/extensions/extension.h b/chrome/common/extensions/extension.h
index 5e7df6f22ccd5af20b092ece7928e26092a18cf2..2e68ab15da94fb5b1244064291836af694d5b3b8 100644
--- a/chrome/common/extensions/extension.h
+++ b/chrome/common/extensions/extension.h
@@ -42,14 +42,16 @@ class DictionaryValue;
 class ListValue;
 }
 
-namespace extensions {
-class Manifest;
-}
-
 namespace webkit_glue {
 struct WebIntentServiceData;
 }
 
+FORWARD_DECLARE_TEST(TabStripModelTest, Apps);
+
+namespace extensions {
+
+class Manifest;
+
 // Represents a Chrome extension.
 class Extension : public base::RefCountedThreadSafe<Extension> {
  public:
@@ -1062,7 +1064,7 @@ class Extension : public base::RefCountedThreadSafe<Extension> {
   std::string content_security_policy_;
 
   FRIEND_TEST_ALL_PREFIXES(ExtensionTest, LoadPageActionHelper);
-  FRIEND_TEST_ALL_PREFIXES(TabStripModelTest, Apps);
+  FRIEND_TEST_ALL_PREFIXES(::TabStripModelTest, Apps);
 
   DISALLOW_COPY_AND_ASSIGN(Extension);
 };
@@ -1124,4 +1126,6 @@ struct UpdatedExtensionPermissionsInfo {
       Reason reason);
 };
 
+} // namespace extensions
+
 #endif  // CHROME_COMMON_EXTENSIONS_EXTENSION_H_