Re-enable DoneCallbackCalledOnOkButtonPressed test

This test was disabled due to flakiness on Windows7 sp1.

BUG=644614

Change-Id: Id48da1b956c38681d1aa16d0a8de95155fc875a2
Reviewed-on: https://chromium-review.googlesource.com/c/1345416Reviewed-by: Qiang Chen <qiangchen@chromium.org>
Commit-Queue: Wei Li <weili@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611368}

chrome/browser/ui/views/desktop_capture/desktop_media_picker_views_unittest.cc

@@ -102,14 +102,7 @@ TEST_F(DesktopMediaPickerViewsTest, DoneCallbackCalledWhenWindowClosed) {
   base::RunLoop().RunUntilIdle();
 }
 
-// Flaky on Windows. https://crbug.com/644614
-#if defined(OS_WIN)
-#define MAYBE_DoneCallbackCalledOnOkButtonPressed DISABLED_DoneCallbackCalledOnOkButtonPressed
-#else
-#define MAYBE_DoneCallbackCalledOnOkButtonPressed DoneCallbackCalledOnOkButtonPressed
-#endif
-
-TEST_F(DesktopMediaPickerViewsTest, MAYBE_DoneCallbackCalledOnOkButtonPressed) {
+TEST_F(DesktopMediaPickerViewsTest, DoneCallbackCalledOnOkButtonPressed) {
   const DesktopMediaID kFakeId(DesktopMediaID::TYPE_WINDOW, 222);
   EXPECT_CALL(*this, OnPickerDone(kFakeId));