Null-check GetView before using it in GetFocusedRenderWidgetHost.

content/browser/renderer_host/render_widget_host_view_mac.mm

 // Copyright (c) 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 "content/browser/renderer_host/render_widget_host_view_mac.h"
 
 #import <objc/runtime.h>
 #include <OpenGL/gl.h>
 #include <QuartzCore/QuartzCore.h>
 #include <utility>
@@ skipping 2091 matching lines @@
     if (parent)
       parent->cocoa_view()->suppressNextEscapeKeyUp_ = YES;
     widgetHost->Shutdown();
     return;
   }
 
   // If there are multiple widgets on the page (such as when there are
   // out-of-process iframes), pick the one that should process this event.
   if (widgetHost->delegate())
     widgetHost = widgetHost->delegate()->GetFocusedRenderWidgetHost(widgetHost);
+  if (!widgetHost)
+    return;
 
   // Suppress the escape key up event if necessary.
   if (event.windowsKeyCode == ui::VKEY_ESCAPE && suppressNextEscapeKeyUp_) {
     if (event.type == NativeWebKeyboardEvent::KeyUp)
       suppressNextEscapeKeyUp_ = NO;
     return;
   }
 
   // Do not forward key up events unless preceded by a matching key down,
   // otherwise we might get an event from releasing the return key in the
@@ skipping 1320 matching lines @@
 
 // "-webkit-app-region: drag | no-drag" is implemented on Mac by excluding
 // regions that are not draggable. (See ControlRegionView in
 // native_app_window_cocoa.mm). This requires the render host view to be
 // draggable by default.
 - (BOOL)mouseDownCanMoveWindow {
   return YES;
 }
 
 @end