Move Extension into extensions namespace

chrome/browser/extensions/extension_tab_helper.h

Index: chrome/browser/extensions/extension_tab_helper.h
diff --git a/chrome/browser/extensions/extension_tab_helper.h b/chrome/browser/extensions/extension_tab_helper.h
index 16b4f5fcb391e9fe356ea6ada4ca0db3be3c0c53..c8a2c4f2c92350ac2ed0787d09f1b7ebe1f4f78a 100644
--- a/chrome/browser/extensions/extension_tab_helper.h
+++ b/chrome/browser/extensions/extension_tab_helper.h
@@ -15,7 +15,6 @@
 #include "content/public/browser/web_contents_observer.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 
-class Extension;
 class ExtensionTabHelperDelegate;
 class TabContentsWrapper;
 struct WebApplicationInfo;
@@ -24,6 +23,10 @@ namespace content {
 struct LoadCommittedDetails;
 }
 
+namespace extensions {
+class Extension;
+}
+
 // Per-tab extension helper. Also handles non-extension apps.
 class ExtensionTabHelper
     : public content::WebContentsObserver,
@@ -59,7 +62,7 @@ class ExtensionTabHelper
   // NOTE: this should only be manipulated before the tab is added to a browser.
   // TODO(sky): resolve if this is the right way to identify an app tab. If it
   // is, than this should be passed in the constructor.
-  void SetExtensionApp(const Extension* extension);
+  void SetExtensionApp(const extensions::Extension* extension);
 
   // Convenience for setting the app extension by id. This does nothing if
   // |extension_app_id| is empty, or an extension can't be found given the
@@ -69,7 +72,7 @@ class ExtensionTabHelper
   // Set just the app icon, used by panels created by an extension.
   void SetExtensionAppIconById(const std::string& extension_app_id);
 
-  const Extension* extension_app() const { return extension_app_; }
+  const extensions::Extension* extension_app() const { return extension_app_; }
   bool is_app() const { return extension_app_ != NULL; }
   const WebApplicationInfo& web_app_info() const {
     return web_app_info_;
@@ -126,9 +129,10 @@ class ExtensionTabHelper
 
   // Resets app_icon_ and if |extension| is non-null creates a new
   // ImageLoadingTracker to load the extension's image.
-  void UpdateExtensionAppIcon(const Extension* extension);
+  void UpdateExtensionAppIcon(const extensions::Extension* extension);
 
-  const Extension* GetExtension(const std::string& extension_app_id);
+  const extensions::Extension* GetExtension(
+      const std::string& extension_app_id);
 
   // ImageLoadingTracker::Observer.
   virtual void OnImageLoaded(const gfx::Image& image,
@@ -155,7 +159,7 @@ class ExtensionTabHelper
 
   // If non-null this tab is an app tab and this is the extension the tab was
   // created for.
-  const Extension* extension_app_;
+  const extensions::Extension* extension_app_;
 
   // Icon for extension_app_ (if non-null) or a manually-set icon for
   // non-extension apps.