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

Index: chrome/browser/ui/views/tab_contents/native_tab_contents_container_aura.cc
diff --git a/chrome/browser/ui/views/tab_contents/native_tab_contents_container_aura.cc b/chrome/browser/ui/views/tab_contents/native_tab_contents_container_aura.cc
index d010d6eefe39d2e28f56d21511723b4acc429ca6..e53e9700507195b6bd9fff0a0948f52a4a810fd2 100644
--- a/chrome/browser/ui/views/tab_contents/native_tab_contents_container_aura.cc
+++ b/chrome/browser/ui/views/tab_contents/native_tab_contents_container_aura.cc
@@ -113,6 +113,7 @@ void NativeTabContentsContainerAura::RequestFocus() {
   // 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,