Disable flaky ExtensionPreferenceApiTest.DataReductionProxy on Windows.

BUG=477844
TBR=kundaji@chromium.org

Review URL: https://codereview.chromium.org/1097623002

Cr-Commit-Position: refs/heads/master@{#325555}

chrome/browser/extensions/api/preference/preference_apitest.cc

@@ -334,7 +334,12 @@ IN_PROC_BROWSER_TEST_F(ExtensionPreferenceApiTest, OnChangeSplit) {
   EXPECT_TRUE(catcher_incognito.GetNextResult()) << catcher.message();
 }
 
-IN_PROC_BROWSER_TEST_F(ExtensionPreferenceApiTest, DataReductionProxy) {
+#if defined(OS_WIN)  // http://crbug.com/477844
+#define MAYBE_DataReductionProxy DISABLED_DataReductionProxy
+#else
+#define MAYBE_DataReductionProxy DataReductionProxy
+#endif
+IN_PROC_BROWSER_TEST_F(ExtensionPreferenceApiTest, MAYBE_DataReductionProxy) {
   EXPECT_TRUE(RunExtensionTest("preference/data_reduction_proxy")) <<
       message_;
 }