Clear VR feedback shared prefs before test start

Clears the two VR feedback shared preference values before a test starts
if they aren't currently the default. This is to prevent flakiness in
VrFeedbackInfoBarTest#* since shared preference settings are not
automatically reset between tests (which is expected).

Bug: 875977
Change-Id: Ic69cadd2ae43b1a3570ee9f349f2770fed812138
Reviewed-on: https://chromium-review.googlesource.com/1183816Reviewed-by: Michael Thiessen <mthiesse@chromium.org>
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585073}

chrome/android/javatests/src/org/chromium/chrome/browser/vr/util/VrTestRuleUtils.java

@@ -12,6 +12,7 @@ import org.junit.runner.Description;
 import org.junit.runners.model.Statement;
 
 import org.chromium.base.test.params.ParameterSet;
+import org.chromium.chrome.browser.vr.VrFeedbackStatus;
 import org.chromium.chrome.browser.vr.rules.ChromeTabbedActivityVrTestRule;
 import org.chromium.chrome.browser.vr.rules.CustomTabActivityVrTestRule;
 import org.chromium.chrome.browser.vr.rules.VrTestRule;
@@ -56,6 +57,17 @@ public class VrTestRuleUtils extends XrTestRuleUtils {
         // IllegalStateException for being used from a backgrounded app.
         VrSettingsServiceUtils.checkForAndApplyVrSettingsFileAnnotation(desc, rule);
 
+        // Reset the VR feedback shared preferences if they're not currently the default because
+        // otherwise we can run into issues with VrFeedbackInfoBarTest#* erroneously failing due to
+        // tests being non-hermetic. Only set if not the default instead of unconditionally in order
+        // to avoid unnecessary disk writes.
+        if (VrFeedbackStatus.getFeedbackOptOut()) {
+            VrFeedbackStatus.setFeedbackOptOut(false);
+        }
+        if (VrFeedbackStatus.getUserExitedAndEntered2DCount() != 0) {
+            VrFeedbackStatus.setUserExitedAndEntered2DCount(0);
+        }
+
         try {
             base.evaluate();
         } finally {