ash: Disable MirrorToDockedWithFullscreen on Windows.

The test creates multiple-displays, and multi-display tests do not work reliably
on Windows.

BUG=none
R=oshima@chromium.org

Review URL: https://codereview.chromium.org/410943003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@284931 0039d316-1c4b-4281-b951-d872f2087c98

ash/display/display_controller_unittest.cc

@@ -550,6 +550,9 @@ DisplayInfo CreateDisplayInfo(int64 id,
 }  // namespace
 
 TEST_F(DisplayControllerTest, MirrorToDockedWithFullscreen) {
+  if (!SupportsMultipleDisplays())
+    return;
+
   // Creates windows to catch activation change event.
   scoped_ptr<aura::Window> w1(CreateTestWindowInShellWithId(1));
   w1->Focus();