Simple fix preventing a potential crash location when shifting focus …

…from an experimental extension popup view.

BUG=NONE
TEST=ExtensionApiTest.Popup

Review URL: http://codereview.chromium.org/5733002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@68814 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/extensions/extension_popup_api.cc

@@ -243,6 +243,12 @@ class ExtensionPopupHost : public ExtensionPopup::Observer,
     // If no view is to be focused, then Chrome was deactivated, so hide the
     // popup.
     if (focused_now) {
+      // On XP, the focus change handler may be invoked when the delegate has
+      // already been revoked.
+      // TODO(twiz@chromium.org):  Resolve the trigger of this behaviour.
+      if (!dispatcher_ || !dispatcher_->delegate())
+        return;
+
       gfx::NativeView host_view =
           dispatcher_->delegate()->GetNativeViewOfHost();