Fix a crash which occurs while dragging tabs back to the window where they originated from.

content/browser/renderer_host/render_widget_host_view_aura.cc

 // 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_aura.h"
 
 #include "base/auto_reset.h"
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/callback_helpers.h"
@@ skipping 567 matching lines @@
   }
 
   delegated_frame_host_->WasShown(browser_latency_info);
 
 #if defined(OS_WIN)
   if (legacy_render_widget_host_HWND_) {
     // Reparent the legacy Chrome_RenderWidgetHostHWND window to the parent
     // window before reparenting any plugins. This ensures that the plugin
     // windows stay on top of the child Zorder in the parent and receive
     // mouse events, etc.
-    legacy_render_widget_host_HWND_->UpdateParent(
-        GetNativeView()->GetHost()->GetAcceleratedWidget());
+    if (GetNativeView()->GetHost()) {

[sky, 2014/09/22 14:57:36]

If this isn't true, when does the parent get updated?

[ananta, 2014/09/22 15:12:18]

4On 2014/09/22 14:57:36, sky wrote:
This should not happen with the other change in this patch. Will revert this
file

+      legacy_render_widget_host_HWND_->UpdateParent(
+          GetNativeView()->GetHost()->GetAcceleratedWidget());
+    }
     legacy_render_widget_host_HWND_->SetBounds(
         window_->GetBoundsInRootWindow());
   }
   LPARAM lparam = reinterpret_cast<LPARAM>(this);
   EnumChildWindows(ui::GetHiddenWindow(), ShowWindowsCallback, lparam);
 #endif
 }
 
 void RenderWidgetHostViewAura::WasHidden() {
   if (!host_ || host_->is_hidden())
@@ skipping 1903 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // RenderWidgetHostViewBase, public:
 
 // static
 void RenderWidgetHostViewBase::GetDefaultScreenInfo(WebScreenInfo* results) {
   GetScreenInfoForWindow(results, NULL);
 }
 
 }  // namespace content