Disable WebRtcSimulcastBrowserTest.TestVgaReturnsTwoSimulcastStreams on Chrome OS

It fails on the official builders.

NOTRY=true
TBR=kjellander@chromium.org
BUG=452623

Review URL: https://codereview.chromium.org/858153004

Cr-Commit-Position: refs/heads/master@{#313640}

chrome/browser/media/chrome_webrtc_simulcast_browsertest.cc

@@ -41,9 +41,9 @@ class WebRtcSimulcastBrowserTest : public WebRtcTestBase {
   }
 };
 
-// Fails/times out on Win only.  http://crbug.com/452623
+// Fails/times out on Windows and Chrome OS. http://crbug.com/452623
 // MSan reports errors. http://crbug.com/452892
-#if defined(OS_WIN) || defined(MEMORY_SANITIZER)
+#if defined(OS_WIN) || defined(OS_CHROMEOS) || defined(MEMORY_SANITIZER)
 #define MAYBE_TestVgaReturnsTwoSimulcastStreams DISABLED_TestVgaReturnsTwoSimulcastStreams
 #else
 #define MAYBE_TestVgaReturnsTwoSimulcastStreams TestVgaReturnsTwoSimulcastStreams