[cros] Change how login-prompt-visible signal is emitted when accelerated compositing is enabled.

chrome/browser/chromeos/login/webui_login_view.h

Index: chrome/browser/chromeos/login/webui_login_view.h
diff --git a/chrome/browser/chromeos/login/webui_login_view.h b/chrome/browser/chromeos/login/webui_login_view.h
index a1585df503f30d22fe93d8fb79bb79674c788a35..b79c7a5058bdc9441373559ef1d634141ca045e1 100644
--- a/chrome/browser/chromeos/login/webui_login_view.h
+++ b/chrome/browser/chromeos/login/webui_login_view.h
@@ -111,6 +111,16 @@ class WebUILoginView : public views::WidgetDelegateView,
       const content::WebContents* source) const OVERRIDE;
   virtual bool TakeFocus(bool reverse) OVERRIDE;
 
+  // Returs true is accelerated compositing is enabled for sign in.
+  bool IsAcceleratedCompositingEnabled();
+
+  // Performs series of action when login prompt is considered
+  // to be ready and visible.
+  // 1. Resets TabRenderWatcher instance.
+  // 2. Emits LoginPromptVisible signal if needed
+  // 3. Notifies OOBE/sign classes.
+  void OnLoginPromptVisible();
+
   // Called when focus is returned from status area.
   // |reverse| is true when focus is traversed backwards (using Shift-Tab).
   void ReturnFocus(bool reverse);
@@ -142,6 +152,9 @@ class WebUILoginView : public views::WidgetDelegateView,
   // first.
   bool login_page_is_loaded_;
 
+  // True if OnLoginPromptVisible() has been called.
+  bool login_prompt_visible_notified_;
+
   // Should we emit the login-prompt-visible signal when the login page is
   // displayed?
   bool should_emit_login_prompt_visible_;