Instant: Use only one hidden WebContents per profile.

chrome/browser/instant/instant_overlay_controller.cc

Index: chrome/browser/instant/instant_overlay_controller.cc
diff --git a/chrome/browser/instant/instant_overlay_controller.cc b/chrome/browser/instant/instant_overlay_controller.cc
index 2ecaff9a51dc7aa1d6f33e3d6ff943ba09fb3216..5e29d8ea9b66008e7b605b07c2aa899308b2c3be 100644
--- a/chrome/browser/instant/instant_overlay_controller.cc
+++ b/chrome/browser/instant/instant_overlay_controller.cc
@@ -4,16 +4,17 @@
 
 #include "chrome/browser/instant/instant_overlay_controller.h"
 
+#include "chrome/browser/instant/instant_controller.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_instant_controller.h"
 
 InstantOverlayController::InstantOverlayController(Browser* browser)
     : browser_(browser) {
   if (browser_->instant_controller())
-    browser_->instant_controller()->instant()->model()->AddObserver(this);
+    browser_->instant_controller()->instant()->AddOverlayModelObserver(this);
 }
 
 InstantOverlayController::~InstantOverlayController() {
   if (browser_->instant_controller())
-    browser_->instant_controller()->instant()->model()->RemoveObserver(this);
+    browser_->instant_controller()->instant()->RemoveOverlayModelObserver(this);
 }