Allow the RWHVW to be focused when a window is restored from minimized.

ui/views/widget/native_widget_win.cc

Index: ui/views/widget/native_widget_win.cc
===================================================================
--- ui/views/widget/native_widget_win.cc	(revision 137127)
+++ ui/views/widget/native_widget_win.cc	(working copy)
@@ -38,6 +38,7 @@
 #include "ui/views/drag_utils.h"
 #include "ui/views/focus/accelerator_handler.h"
 #include "ui/views/focus/view_storage.h"
+#include "ui/views/focus/widget_focus_manager.h"
 #include "ui/views/ime/input_method_win.h"
 #include "ui/views/views_delegate.h"
 #include "ui/views/widget/aero_tooltip_manager.h"
@@ -1332,6 +1333,7 @@
 
   // Get access to a modifiable copy of the system menu.
   GetSystemMenu(hwnd(), false);
+
   return 0;
 }
 
@@ -2255,6 +2257,18 @@
       widget->restore_focus_when_enabled_ = true;
       return;
     }
+
+    // Mysteriously, this only appears to be needed support restoration of focus
+    // to a child hwnd when restoring its top level window from the minimized
+    // state. If we don't do this, then ::SetFocus() to that child HWND returns
+    // ERROR_INVALID_PARAMETER, despite both HWNDs being of the same thread.
+    // See http://crbug.com/125976
+    {
+      // Since this is a synthetic reset, we don't need to tell anyone about it.
+      AutoNativeNotificationDisabler disabler;
+      focus_manager->ClearFocus();
+    }
+
     focus_manager->RestoreFocusedView();
   }
 }