MacViews: Explicitly release mouse capture in BridgedNativeWidget::OnWindowWillClose().

ui/views/widget/widget_unittest.cc

Index: ui/views/widget/widget_unittest.cc
diff --git a/ui/views/widget/widget_unittest.cc b/ui/views/widget/widget_unittest.cc
index 8761f7f5cc83857e0164d4f81eb654e02b4c555d..373aa137511177e63b9f126e92f83f15c7b85921 100644
--- a/ui/views/widget/widget_unittest.cc
+++ b/ui/views/widget/widget_unittest.cc
@@ -1774,6 +1774,15 @@ TEST_F(WidgetTest, MousePressCausesCapture) {
   widget->CloseNow();
 }
 
+// Verify capture is correctly set on a widget. Test for crbug.com/622201.

[tapted, 2016/06/23 02:26:28]

This doesn't describe the test well. It should be something like "Test to ensure
capture is correctly released from a Widget with capture when it is destroyed."

[karandeepb, 2016/06/23 07:58:32]

Done.

+TEST_F(WidgetTest, VerifyWindowCapture) {
+  Widget* widget = CreateTopLevelNativeWidget();

[tapted, 2016/06/23 02:26:28]

We should use CreateNativeDesktopWidget() for better coverage. But it will
probably mean that the test needs to go into widget_interactive_uitest.cc

[karandeepb, 2016/06/23 07:58:32]

Why is moving to widget_interactive_uitest.cc needed? Also between
CreateNativeDesktopWidget/CreateTopLevelNativeWidget, isn't it just that one
uses DesktopNativeWidgetAura and the other NativeWidgetAura?

[tapted, 2016/06/24 07:11:58]

Capture has complex interactions with the OS sometimes. E.g. I think that
another window activating on Windows can cause capture to be lost unexpectedly.
Yup. The problem is that testing NativeWidgetAura on Windows/Linux tends not to
be very exciting - we miss out on a lot of coverage, and it's somewhat redundant
with the tests also running on ChromeOS. Desktop Widgets mean not only
DesktopNativeWidgetAura gets coverage, but also DesktopWindowTreeHostX11
DesktopWindowTreeHostWin HWNDMessageHandler and a bunch of other things

I actually want to convert more of the widget_unittests to be parameterized so
they run both with/without desktop widgets. I think I made a bug for it..
somewhere.

+  widget->Show();
+  widget->native_widget_private()->SetCapture();
+  EXPECT_TRUE(widget->HasCapture());
+  widget->CloseNow();

[tapted, 2016/06/23 02:26:28]

We should test asynchronous Close() as well, since the codepath is pretty
different.

We should probably also test InitParams::WIDGET_OWNS_NATIVE_WIDGET :/

[karandeepb, 2016/06/23 07:58:32]

Done.

+}
+
 namespace {
 
 // An EventHandler which shows a Wiget upon receiving a mouse event. The Widget