Alternate NTP: Fix bug where shadow is not removed

chrome/browser/ui/cocoa/tab_contents/instant_preview_controller_mac.mm

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/cocoa/tab_contents/instant_preview_controller_mac.h"
 
 #include "chrome/browser/instant/instant_model.h"
 #include "chrome/browser/ui/browser.h"
 #import "chrome/browser/ui/cocoa/browser_window_controller.h"
 #import "chrome/browser/ui/cocoa/tab_contents/previewable_contents_controller.h"
@@ skipping 11 matching lines @@
 }
 
 void InstantPreviewControllerMac::PreviewStateChanged(
     const InstantModel& model) {
   if (model.mode().is_ntp() || model.mode().is_search_suggestions()) {
     // Drop shadow is only needed if search mode is not |NTP| and preview does
     // not fill up the entire contents page.
     BOOL drawDropShadow = !model.mode().is_ntp() &&
         !(model.height() == 100 &&
           model.height_units() == INSTANT_SIZE_PERCENT);
-    [preview_ showPreview:model.GetPreviewContents()
-                   height:model.height()
-              heightUnits:model.height_units()
-           drawDropShadow:drawDropShadow];
+    [preview_ setPreview:model.GetPreviewContents()
+                  height:model.height()
+             heightUnits:model.height_units()
+          drawDropShadow:drawDropShadow];
   } else {
-    [preview_ hidePreview];
+    [preview_ setPreview:NULL
+                  height:0
+             heightUnits:INSTANT_SIZE_PIXELS
+          drawDropShadow:NO];
   }
   browser_->MaybeUpdateBookmarkBarStateForInstantPreview(model.mode());
   [window_ updateBookmarkBarStateForInstantPreview];
 }