Always enable FCM on Windows.

content/browser/gpu/compositor_util_browsertest.cc

Index: content/browser/gpu/compositor_util_browsertest.cc
diff --git a/content/browser/gpu/compositor_util_browsertest.cc b/content/browser/gpu/compositor_util_browsertest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c628218e91019e890f7c56e28173c17806d05e9f
--- /dev/null
+++ b/content/browser/gpu/compositor_util_browsertest.cc
@@ -0,0 +1,41 @@
+// Copyright (c) 2013 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 "content/public/browser/compositor_util.h"
+#include "content/test/content_browser_test.h"
+
+#if defined(OS_WIN)
+#include "base/win/windows_version.h"
+#endif
+
+namespace content {
+
+typedef ContentBrowserTest CompositorUtilTest;
+
+// Test that threaded compositing and FCM are in the expected mode on the bots
+// for all platforms.
+IN_PROC_BROWSER_TEST_F(CompositorUtilTest, CompositingModeAsExpected) {

[gab, 2013/08/15 20:07:49]

The only thing that scares me about this test is that it is not impossible for
this scenario to happen:

- Tests are sharded.
- The bot running this test is in the right config and passes.
- Another bot not running this particular test is in the wrong config and we
don't know (or get flaky test results).

The only way I see to fix this is to hook into BrowserTestBase to make sure this
is always correct before running any such tests.

Does this concern worry you or are we confident that a set of bots running
sharded tests have identical configs?

[Zhenyao Mo, 2013/08/15 20:23:37]

I think it is OK.  I assume with sharding, we still will at least run this more
than once per day, which guards against regression.

+  enum CompositingMode {
+    DISABLED,
+    ENABLED,
+    THREADED,
+  } expected_mode = DISABLED;
+#if defined(OS_CHROMEOS)
+  expected_mode = THREADED;
+#elif defined(OS_WIN)
+#if defined(USE_AURA)
+  // WinAura always uses threaded compositing.
+  expected_mode = THREADED;
+#else  // defined(USE_AURA)
+  if (base::win::GetVersion() >= base::win::VERSION_VISTA)
+    expected_mode = ENABLED;
+#endif  // defined(USE_AURA)
+#endif
+
+  EXPECT_EQ(expected_mode == ENABLED || expected_mode == THREADED,
+            IsForceCompositingModeEnabled());
+  EXPECT_EQ(expected_mode == THREADED, IsThreadedCompositingEnabled());
+}
+
+}