Fix partial screenshot/window screenshot when holding Alt+Tab.

ash/utility/screenshot_controller_unittest.cc

Index: ash/utility/screenshot_controller_unittest.cc
diff --git a/ash/utility/screenshot_controller_unittest.cc b/ash/utility/screenshot_controller_unittest.cc
index b7e9ddac3701ba8fd53a705bee76d3cc3b7e7b95..70466fe9ca0b08ffa69c279096a6562b517943e0 100644
--- a/ash/utility/screenshot_controller_unittest.cc
+++ b/ash/utility/screenshot_controller_unittest.cc
@@ -481,4 +481,15 @@ TEST_F(ScreenshotControllerTest, MultipleDisplays) {
   EXPECT_FALSE(IsActive());
 }
 
+// Windows that take capture can misbehave when a screenshot session starts.
+// See crbug.com/651939
+TEST_F(ScreenshotControllerTest, BreaksCapture) {
+  std::unique_ptr<aura::Window> window(
+      CreateSelectableWindow(gfx::Rect(100, 100, 100, 100)));
+  window->SetCapture();
+  EXPECT_TRUE(window->HasCapture());
+  StartWindowScreenshotSession();
+  EXPECT_FALSE(window->HasCapture());
+}
+
 }  // namespace ash