Mark some tests flaky as they started to fail on GN bot

TBR=yfriedman@chromium.org
BUG=606939,606942

Review URL: https://codereview.chromium.org/1924483003

Cr-Commit-Position: refs/heads/master@{#389894}

chrome/android/javatests/src/org/chromium/chrome/browser/contextmenu/ContextMenuTest.java

@@ -15,6 +15,7 @@ import android.view.KeyEvent;
 
 import org.chromium.base.test.util.CommandLineFlags;
 import org.chromium.base.test.util.Feature;
+import org.chromium.base.test.util.FlakyTest;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.ChromeSwitches;
 import org.chromium.chrome.browser.compositor.layouts.LayoutManager;
@@ -116,9 +117,12 @@ public class ContextMenuTest extends DownloadTestBase {
                 "testImage", "/chrome/test/data/android/contextmenu/test_image.png");
     }
 
-    @MediumTest
-    @Feature({"Browser"})
-    @CommandLineFlags.Add(ChromeSwitches.DISABLE_DOCUMENT_MODE)
+    /**
+     * @MediumTest
+     * @Feature({"Browser"})
+     * @CommandLineFlags.Add(ChromeSwitches.DISABLE_DOCUMENT_MODE)
+    */
+    @FlakyTest(message = "http://crbug.com/606939")
     public void testLongPressOnImageLink() throws InterruptedException, TimeoutException {
         checkOpenImageInNewTab(
                 "testImageLink", "/chrome/test/data/android/contextmenu/test_image.png");

content/public/android/javatests/src/org/chromium/content/browser/ContentViewCoreSelectionTest.java

@@ -448,8 +448,11 @@ public class ContentViewCoreSelectionTest extends ContentShellTestBase {
                 });
     }
 
-    @SmallTest
-    @Feature({"TextSelection", "TextInput"})
+    /**
+     * @SmallTest
+     * @Feature({"TextSelection", "TextInput"})
+     */
+    @FlakyTest(message = "http://crbug.com/606942")
     public void testCursorPositionAfterHidingActionMode() throws Exception {
         DOMUtils.longPressNode(this, mContentViewCore, "textarea");
         waitForSelectActionBarVisible(true);