Instant: Use only one hidden WebContents per profile.

chrome/browser/ui/gtk/browser_window_gtk.h

Index: chrome/browser/ui/gtk/browser_window_gtk.h
diff --git a/chrome/browser/ui/gtk/browser_window_gtk.h b/chrome/browser/ui/gtk/browser_window_gtk.h
index d227e2380a81d7818e88e53600d2b533b3dad332..494b57369c3b0bafe2a1c8243ecc162c38240a4b 100644
--- a/chrome/browser/ui/gtk/browser_window_gtk.h
+++ b/chrome/browser/ui/gtk/browser_window_gtk.h
@@ -38,7 +38,7 @@ class FindBarGtk;
 class FullscreenExitBubbleGtk;
 class GlobalMenuBar;
 class InfoBarContainerGtk;
-class InstantPreviewControllerGtk;
+class InstantOverlayControllerGtk;
 class LocationBar;
 class PrefRegistrySyncable;
 class StatusBubbleGtk;
@@ -509,8 +509,8 @@ class BrowserWindowGtk
   // selected tab contents.
   scoped_ptr<TabContentsContainerGtk> devtools_container_;
 
-  // A sub-controller that manages the Instant preview visual state.
-  scoped_ptr<InstantPreviewControllerGtk> instant_preview_controller_;
+  // A sub-controller that manages the Instant overlay visual state.
+  scoped_ptr<InstantOverlayControllerGtk> instant_overlay_controller_;
 
   // The Extension Keybinding Registry responsible for registering listeners for
   // accelerators that are sent to the window, that are destined to be turned