Make VR screen tap tests more stable

chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/WebVrTest.java

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.vr_shell;
 
 import static org.chromium.chrome.test.util.ChromeRestriction.RESTRICTION_TYPE_VIEWER_DAYDREAM;
 import static org.chromium.chrome.test.util.ChromeRestriction.RESTRICTION_TYPE_VIEWER_NON_DAYDREAM;
 import static org.chromium.chrome.test.util.ChromeRestriction.RESTRICTION_TYPE_WEBVR_SUPPORTED;
 
+import android.os.SystemClock;
 import android.support.test.filters.SmallTest;
 
 import org.chromium.base.Log;
 import org.chromium.base.test.util.CommandLineFlags;
 import org.chromium.base.test.util.Restriction;
 import org.chromium.base.test.util.UrlUtils;
 import org.chromium.chrome.test.ChromeTabbedActivityTestBase;
 import org.chromium.content.browser.test.util.ClickUtils;
 import org.chromium.content.browser.test.util.Criteria;
 import org.chromium.content.browser.test.util.CriteriaHelper;
@@ skipping 221 matching lines @@
         String testName = "test_nfc_fires_vrdisplayactivate";
         loadUrl(getHtmlTestFile(testName), 10);
         simNfcScanAndWait(mWebContents);
         endTest(mWebContents);
     }
 
     /**
      * Tests that screen touches are not registered when the viewer is a
      * Daydream View.
      */
     @SmallTest

[Ted C, 2017/03/27 15:44:06]

This should likely be a LargeTest (and probably should have been a MediumTest
before IMO).

[bsheedy, 2017/03/27 20:19:12]

Done.

     @Restriction(RESTRICTION_TYPE_VIEWER_DAYDREAM)
     public void testScreenTapsNotRegisteredOnDaydream() throws InterruptedException {
         String testName = "test_screen_taps_not_registered_on_daydream";
         loadUrl(getHtmlTestFile(testName), 10);
         assertTrue("VRDisplay found", vrDisplayFound(mWebContents));
         executeStepAndWait("stepVerifyNoInitialTaps()", mWebContents);
         enterVrTapAndWait(mWebContents);
-        enterVrTap();
+        // Checking for a tap in Javascript immediately after sending one can result
+        // in the check happening before the click event is fired, which would cause
+        // this test to pass even if the click would have been registered. Solution
+        // is to send several over a short period to make sure there's enough time
+        for (int i = 0; i < 5; i++) {

[Ted C, 2017/03/27 15:44:06]

What is the goal of the test?  Are we trying to send multiple click events and
see that nothing happens?  In particular, would we want to have this in a loop,
but we don't have a reliable way to delay the next event until the previous one
was sent to the renderer?

If we did have such a mechanism, would we want to send only two events and
ensure the second event wasn't registered? 

I don't have a good suggestion for receiving acks that a event has been
processed (aside from what we suggested and that didn't work for you). 
dtrainor@ suggested there was some thing in content/ that did receive ACKs so we
could look at piping that out.  I'm fine if we want to file a new crbug and add
a TODO here though to make forward progress.

[bsheedy, 2017/03/27 20:19:12]

The purpose is to test that tapping on the screen when we're presenting in WebVR
doesn't fire any click events if the VR viewer is set to Daydream View. Ideally,
we send the first event (before we're presenting in WebVR) to enter VR (we need
a user gesture in order to do so). Then, we send a second event, somehow wait
until we know for sure that the event would have been fired in Javascript by
now, and make sure that it hasn't actually been fired.

I've talked to a couple SWEs working on the VR stuff for Chrome, and it looks
like the touch event is actually being consumed by Daydream's
DaydreamTouchListener when the viewer is set to Daydream View. I'm not exactly
familiar with what exactly that ends up affecting, but I think it doesn't even
make it to content/ in that case. If there's some way to be notified whenever
events get consumed, that could work.

+            enterVrTap();
+            SystemClock.sleep(50);
+        }
         executeStepAndWait("stepVerifyNoAdditionalTaps()", mWebContents);
         endTest(mWebContents);
     }
 
     /**
      * Tests that screen touches are still registered when the viewer is
      * Cardboard.
      */
     @SmallTest
     @Restriction(RESTRICTION_TYPE_VIEWER_NON_DAYDREAM)
     public void testScreenTapsRegisteredOnCardboard() throws InterruptedException {
         String testName = "test_screen_taps_registered_on_cardboard";
         loadUrl(getHtmlTestFile(testName), 10);
         assertTrue("VRDisplay found", vrDisplayFound(mWebContents));
         executeStepAndWait("stepVerifyNoInitialTaps()", mWebContents);
+        // Tap and wait to enter VR
         enterVrTapAndWait(mWebContents);
-        enterVrTap();
-        executeStepAndWait("stepVerifyAdditionalTap()", mWebContents);
+        // Tap and wait for Javascript to receive it
+        enterVrTapAndWait(mWebContents);
         endTest(mWebContents);
     }
 
     /**
      * Tests that non-focused tabs cannot get pose information.
      */
     @SmallTest
     public void testPoseDataUnfocusedTab() throws InterruptedException {
         String testName = "test_pose_data_unfocused_tab";
         loadUrl(getHtmlTestFile(testName), 10);
         assertTrue("VRDisplay found", vrDisplayFound(mWebContents));
         executeStepAndWait("stepCheckFrameDataWhileFocusedTab()", mWebContents);
 
         loadUrlInNewTab("about:blank");
 
         executeStepAndWait("stepCheckFrameDataWhileNonFocusedTab()", mWebContents);
         endTest(mWebContents);
     }
 }