Fix SetShape (SetAlphaShape) to allow Null regions (+ tests).

ui/views/widget/desktop_aura/desktop_window_tree_host_x11_unittest.cc

 // Copyright 2014 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 <vector>
 
 #include <X11/extensions/shape.h>
 #include <X11/Xlib.h>
 
 // Get rid of X11 macros which conflict with gtest.
@@ skipping 289 matching lines @@
   EXPECT_FALSE(ShapeRectContainsPoint(shape_rects, 105, 15));
 
   // Changing the widget's size should not affect the shape.
   widget2->SetBounds(gfx::Rect(100, 100, 200, 200));
   shape_rects = GetShapeRects(xid2);
   ASSERT_FALSE(shape_rects.empty());
   EXPECT_FALSE(ShapeRectContainsPoint(shape_rects, 5, 5));
   EXPECT_TRUE(ShapeRectContainsPoint(shape_rects, 15, 5));
   EXPECT_TRUE(ShapeRectContainsPoint(shape_rects, 95, 15));
   EXPECT_FALSE(ShapeRectContainsPoint(shape_rects, 105, 15));
+
+  // Setting the shape to NULL resets the shape back to the entire
+  // window bounds.
+  widget2->SetShape(NULL);
+  shape_rects = GetShapeRects(xid2);
+  ASSERT_FALSE(shape_rects.empty());
+  EXPECT_TRUE(ShapeRectContainsPoint(shape_rects, 5, 5));
+  EXPECT_TRUE(ShapeRectContainsPoint(shape_rects, 15, 5));
+  EXPECT_TRUE(ShapeRectContainsPoint(shape_rects, 95, 15));
+  EXPECT_TRUE(ShapeRectContainsPoint(shape_rects, 105, 15));
+  EXPECT_FALSE(ShapeRectContainsPoint(shape_rects, 500, 500));
 }
 
 // Test that the widget ignores changes in fullscreen state initiated by the
 // window manager (e.g. via a window manager accelerator key).
 TEST_F(DesktopWindowTreeHostX11Test, WindowManagerTogglesFullscreen) {
   if (!ui::WmSupportsHint(ui::GetAtom("_NET_WM_STATE_FULLSCREEN")))
     return;
 
   scoped_ptr<Widget> widget = CreateWidget(new ShapedWidgetDelegate());
   XID xid = widget->GetNativeWindow()->GetHost()->GetAcceleratedWidget();
@@ skipping 119 matching lines @@
         SubstructureRedirectMask | SubstructureNotifyMask,
         &xevent);
 
     WMStateWaiter waiter(xid, "_NET_WM_STATE_FOCUSED", true);
     waiter.Wait();
   }
   EXPECT_TRUE(widget.GetNativeWindow()->IsVisible());
 }
 
 }  // namespace views