Add way to get native VR UI information from Java

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

Index: chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/VrUtils.java
diff --git a/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/VrUtils.java b/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/VrUtils.java
index 7e5797911605c7419a338e00258528b5395a13ea..ac506981398c0cde6889a47e8b46dfe014f27268 100644
--- a/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/VrUtils.java
+++ b/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/VrUtils.java
@@ -15,6 +15,7 @@ import android.nfc.NfcAdapter;
 import org.chromium.base.ThreadUtils;
 import org.chromium.content.browser.test.util.Criteria;
 import org.chromium.content.browser.test.util.CriteriaHelper;
+import org.chromium.content_public.browser.WebContents;
 
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
@@ -122,4 +123,22 @@ public class VrUtils {
             }
         }), timeout, POLL_CHECK_INTERVAL_SHORT_MS);
     }
+
+    /**
+     * Tries to get the HTML UI WebContents from VrShell.
+     * @param timeout The timeout for getting the WebContents in milliseconds
+     * @return The WebContents for the HTML UI.
+     */
+    public static WebContents getVrShellUiContents(final int timeout) {
+        CriteriaHelper.pollInstrumentationThread(Criteria.equals(true, new Callable<Boolean>() {

[David Trainor- moved to gerrit, 2017/03/30 04:45:38]

Should this be instrumentation thread?  Some of the other calls to
VrShellDelegate are made on the UI thread (waitForVrSupported above for
example).

[bsheedy, 2017/03/30 21:05:14]

I don't think it really matters in this case, but I've changed it to the UI
thread for consistency.

+            @Override
+            public Boolean call() {
+                if (VrShellDelegate.getVrShellForTesting() == null) return false;

[David Trainor- moved to gerrit, 2017/03/30 04:45:38]

VrShellImpl vrShell = (VrShellImpl) VrShellDelegate.getVrShellForTesting();
return vrShell != null && vrShell.getUiContentsForTesting() != null;

[bsheedy, 2017/03/30 21:05:14]

Done.

+                VrShellImpl vrShell = (VrShellImpl) VrShellDelegate.getVrShellForTesting();
+                return vrShell.getUiContentsForTesting() != null;
+            }
+        }), timeout, POLL_CHECK_INTERVAL_LONG_MS);
+        // If we've made it here, then we know that the UI contents exist.
+        return ((VrShellImpl) VrShellDelegate.getVrShellForTesting()).getUiContentsForTesting();

[David Trainor- moved to gerrit, 2017/03/30 04:45:38]

Maybe try AtomicReference and just set it as we poll or something?  Or create a
[1] array that you set the return value on?

[bsheedy, 2017/03/30 21:05:14]

Done. Didn't know about AtomicReference, that could be handy in the future.

+    }
 }