Disable flaky testThemeColorWhenNotSpecified

See bug for details.

TBR: pkotwicz@chromium.org
Bug: 1028628
Change-Id: If6e85886a4c6572fa4874a77f443dcd716fbe72f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1937129Reviewed-by: Matthew Jones <mdjones@chromium.org>
Commit-Queue: Matthew Jones <mdjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#719218}

chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappSplashScreenTest.java

@@ -27,6 +27,7 @@ import org.chromium.base.ApiCompatibilityUtils;
 import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.base.task.PostTask;
 import org.chromium.base.test.util.CommandLineFlags;
+import org.chromium.base.test.util.DisabledTest;
 import org.chromium.base.test.util.Feature;
 import org.chromium.chrome.browser.ChromeSwitches;
 import org.chromium.chrome.browser.ShortcutHelper;
@@ -77,6 +78,7 @@ public class WebappSplashScreenTest {
                 background.getColor());
     }
 
+    @DisabledTest(message = "crbug.com/1028628")
     @Test
     @SmallTest
     @Feature({"Webapps"})