Re-implement the screensaver to use WebView instead of ExtensionDialogHost.

ash/shell_delegate.h

Index: ash/shell_delegate.h
diff --git a/ash/shell_delegate.h b/ash/shell_delegate.h
index 0a86aa33f48183d3a2724d3ecf96af693e23dc08..9cbe304d566cd6e2f0a803d33d2b2cae51b25581 100644
--- a/ash/shell_delegate.h
+++ b/ash/shell_delegate.h
@@ -71,6 +71,9 @@ class ASH_EXPORT ShellDelegate {
   // Invoked when the user needs to set up mobile networking.
   virtual void OpenMobileSetup() = 0;
 
+  // Get the current browser context. This will get us the current profile.
+  virtual content::BrowserContext* GetCurrentBrowserContext() = 0;
+
   // Invoked to create an AppListViewDelegate. Shell takes the ownership of
   // the created delegate.
   virtual AppListViewDelegate* CreateAppListViewDelegate() = 0;