Check that we have a focus manager in aura before trying to set focus.

chrome/browser/ui/views/tab_contents/native_tab_contents_container_aura.cc

 // Copyright (c) 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.
 
 #include "chrome/browser/ui/views/tab_contents/native_tab_contents_container_aura.h"
 
 #include "chrome/browser/ui/view_ids.h"
 #include "chrome/browser/ui/views/tab_contents/tab_contents_container.h"
 #include "chrome/browser/ui/views/tab_contents/tab_contents_view_views.h"
 #include "content/browser/tab_contents/interstitial_page.h"
@@ skipping 95 matching lines @@
 }
 
 void NativeTabContentsContainerAura::RequestFocus() {
   // This is a hack to circumvent the fact that a the OnFocus() method is not
   // invoked when RequestFocus() is called on an already focused view.
   // The TabContentsContainer is the view focused when the TabContents has
   // focus.  When switching between from one tab that has focus to another tab
   // that should also have focus, RequestFocus() is invoked one the
   // TabContentsContainer.  In order to make sure OnFocus() is invoked we need
   // to clear the focus before hands.
+  //  if (GetFocusManager()) {

[alicet1, 2011/12/05 20:21:55]

see the native_tab_contents_view_aura.cc in this CL: if I keep the widget type
to be TYPE_CONTROL, then this native tab content will not be top level and will
not have a focus manager, this line will be needed to check that we have a valud
focus manager. 

[sky, 2011/12/05 21:56:41]

See my second comment in this thread. A views::Widget of TYPE_CONTROL inherits
the FocusManager from an ancestor Widget as long as it's contained in a widget
hierarchy. For a browser window we create a BrowserFrame, which should be marked
as a top level. The only way this check would matter is if, for some reason,
we're invoking RequestFocus and the NativeTabContentsContainerAura does not have
an ancestor. It should be easy to figure that out. Make this a DCHECK and
inspect the ancestors.

[alicet1, 2011/12/06 06:28:51]

updated. per offline discussion, a test browser window in unittest may/may not
have all that we expect from a widget hierarchy, and in the absence of a top
level widget, it is safer to always check for a valid focus manager before
proceed.

   {
     // Disable notifications.  Clear focus will assign the focus to the main
     // browser window.  Because this change of focus was not user requested,
     // don't send it to listeners.
     views::AutoNativeNotificationDisabler local_notification_disabler;
     GetFocusManager()->ClearFocus();
   }
   View::RequestFocus();
 }
 
@@ skipping 15 matching lines @@
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // NativeTabContentsContainer, public:
 
 // static
 NativeTabContentsContainer* NativeTabContentsContainer::CreateNativeContainer(
     TabContentsContainer* container) {
   return new NativeTabContentsContainerAura(container);
 }