Move NativeAppWindow to extensions

apps/ui/apps_client.h

Index: apps/ui/apps_client.h
diff --git a/apps/ui/apps_client.h b/apps/ui/apps_client.h
index 2f26dbcf05d8fba9b72135e59d7ab86572842fd9..da4b2bf8d1fe4ca48f1532f3f58a0815105d512c 100644
--- a/apps/ui/apps_client.h
+++ b/apps/ui/apps_client.h
@@ -15,12 +15,11 @@ class BrowserContext;
 
 namespace extensions {
 class Extension;
+class NativeAppWindow;
 }
 
 namespace apps {
 
-class NativeAppWindow;
-
 // Sets up global state for the apps system. Should be Set() once in each
 // process. This should be implemented by the client of the apps system.
 class AppsClient {
@@ -34,8 +33,8 @@ class AppsClient {
       content::BrowserContext* context,
       const extensions::Extension* extension) = 0;
 
-  // Creates a new apps::NativeAppWindow for |window|.
-  virtual NativeAppWindow* CreateNativeAppWindow(
+  // Creates a new extensions::NativeAppWindow for |window|.
+  virtual extensions::NativeAppWindow* CreateNativeAppWindow(
       AppWindow* window,
       const AppWindow::CreateParams& params) = 0;