Speculative fix for instant overlay crash

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

 // Copyright 2011 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.
 
 #import "chrome/browser/ui/cocoa/tab_contents/overlayable_contents_controller.h"
 
 #include "base/mac/bundle_locations.h"
 #include "chrome/browser/ui/cocoa/browser_window_controller.h"
 #include "chrome/browser/ui/cocoa/tab_contents/instant_overlay_controller_mac.h"
 #include "chrome/browser/ui/cocoa/tab_contents/overlay_separator_view.h"
@@ skipping 112 matching lines @@
 }
 
 - (BOOL)isShowingOverlay {
   return overlayContents_ != nil;
 }
 
 - (InstantOverlayControllerMac*)instantOverlayController {
   return instantOverlayController_.get();
 }
 
+- (void)onWebContentsDestroyed:(content::WebContents*)webContents {
+  if (overlayContents_ == webContents) {
+    [overlayContents_->GetView()->GetNativeView() removeFromSuperview];
+    overlayContents_ = NULL;
+  }
+}
+
 - (NSView*)activeContainer {
   return activeContainer_.get();
 }
 
 - (NSView*)dropShadowView {
   return dropShadowView_.get();
 }
 
 - (void)setActiveContainerOffset:(CGFloat)activeContainerOffset {
   if (activeContainerOffset_ == activeContainerOffset)
@@ skipping 76 matching lines @@
 
   if (![windowController_ hasToolbar])
     return NO;
 
   // Show a separator is the overlay or the tab contents will be shown right
   // next to the omnibox.
   return activeContainerOffset_ == 0 || overlayContents_;
 }
 
 @end