[Android] Mark InstallerDelegateTest#testRunnableRaceCondition as flaky

This test appears to fail occasionally on instrumentation-occam-svelte-clankium.

BUG=542627
TBR=dfalcantara@chromium.org,aurimas@chromium.org

Review URL: https://codereview.chromium.org/1402813004

Cr-Commit-Position: refs/heads/master@{#353720}

chrome/android/javatests/src/org/chromium/chrome/browser/banners/InstallerDelegateTest.java

@@ -6,6 +6,7 @@
 
 import android.content.pm.PackageInfo;
 import android.os.HandlerThread;
+import android.test.FlakyTest;
 import android.test.InstrumentationTestCase;
 import android.test.mock.MockPackageManager;
 import android.test.suitebuilder.annotation.SmallTest;
@@ -158,6 +159,8 @@ public void testInstallTimeout() throws InterruptedException {
     /**
      * Makes sure that the runnable isn't called until returning from start().
      */
+    /* Appears to be flaky crbug.com/542627 */
+    @FlakyTest
     @SmallTest
     public void testRunnableRaceCondition() throws InterruptedException {
         mPackageManager.isInstalled = true;