Fix unresponsive browser due to a crashed plugin with a modal dialog.

If a plugin dies with an open modal window the browser window will not be enabled. So, we re-enable the browser if it's ever disabled without any child dialogs.

BUG=90002
TEST=Kill the Flash process while a modal dialog (e.g. file, print) is open. Browser should remain responsive.
Review URL: http://codereview.chromium.org/7812005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@98875 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/hang_monitor/hung_window_detector.cc

@@ -59,6 +59,14 @@ void HungWindowDetector::OnTick() {
 
   EnumChildWindows(top_level_window_, ChildWndEnumProc,
                    reinterpret_cast<LPARAM>(this));
+
+  // The window shouldn't be disabled unless we're showing a modal dialog.
+  // If we're not, then reenable the window.
+  if (!::IsWindowEnabled(top_level_window_) &&
+      !::GetWindow(top_level_window_, GW_ENABLEDPOPUP)) {
+    ::EnableWindow(top_level_window_, TRUE);
+  }
+
   enumerating_ = false;
 }