Expose VSync pausing through WindowAndroid and pause VSync during webVR presentation

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

+// Copyright 2013 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.content.browser;
+
+import android.support.test.filters.MediumTest;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.chromium.base.ThreadUtils;
+import org.chromium.base.test.BaseJUnit4ClassRunner;
+import org.chromium.base.test.util.CallbackHelper;
+import org.chromium.base.test.util.UrlUtils;
+import org.chromium.content.browser.test.util.JavaScriptUtils;
+import org.chromium.content_public.browser.WebContentsObserver;
+import org.chromium.content_shell_apk.ContentShellActivity;
+import org.chromium.content_shell_apk.ContentShellActivityTestRule;
+
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+/**
+ * Tests pausing the VSync loop for a WindowAndroid.
+ */
+@RunWith(BaseJUnit4ClassRunner.class)
+public class VSyncPausedTest {
+    @Rule
+    public ContentShellActivityTestRule mActivityTestRule = new ContentShellActivityTestRule();
+
+    private static final String VSYNC_HTML = "content/test/data/android/vsync.html";
+    private static final String CALL_RAF = "window.requestAnimationFrame(onAnimationFrame);";
+
+    private CallbackHelper mOnTitleUpdatedHelper;
+    private String mTitle;
+
+    private WebContentsObserver mObserver;
+    private ContentShellActivity mActivity;
+
+    @Before
+    public void setUp() throws Exception {
+        mActivity = mActivityTestRule.launchContentShellWithUrl(
+                UrlUtils.getIsolatedTestFileUrl(VSYNC_HTML));
+        mActivityTestRule.waitForActiveShellToBeDoneLoading();
+        mObserver = new WebContentsObserver(mActivity.getActiveWebContents()) {
+            @Override
+            public void titleWasSet(String title) {
+                mTitle = title;
+                mOnTitleUpdatedHelper.notifyCalled();
+            }
+        };
+        mOnTitleUpdatedHelper = new CallbackHelper();
+    }
+
+    @Test
+    @MediumTest
+    public void testPauseVSync() throws Throwable {
+        int callCount = mOnTitleUpdatedHelper.getCallCount();
+        JavaScriptUtils.executeJavaScriptAndWaitForResult(
+                mActivity.getActiveWebContents(), CALL_RAF);
+        mOnTitleUpdatedHelper.waitForCallback(callCount);
+        Assert.assertEquals("1", mTitle);
+        ThreadUtils.runOnUiThreadBlocking(new Runnable() {
+            @Override
+            public void run() {
+                mActivity.getActiveShell().getContentViewCore().getWindowAndroid().setVSyncPaused(
+                        true);
+            }
+        });
+        // There may be a VSync already propagating before we pause VSync, so we need a short delay
+        // to let it finish propagating and prevent flakes.
+        Thread.sleep(100);

[boliu, 2017/03/16 02:28:52]

err, no sleeps, which is a recipe for flakes

maybe we can do this part in a loop?

[mthiesse, 2017/03/16 15:36:06]

Found a better solution.

+        callCount = mOnTitleUpdatedHelper.getCallCount();
+        JavaScriptUtils.executeJavaScriptAndWaitForResult(
+                mActivity.getActiveWebContents(), CALL_RAF);
+        try {
+            mOnTitleUpdatedHelper.waitForCallback(callCount, 1, 1, TimeUnit.SECONDS);
+        } catch (TimeoutException e) {
+            // Timeout is expected.
+        }
+        Assert.assertEquals("1", mTitle);
+        ThreadUtils.runOnUiThreadBlocking(new Runnable() {
+            @Override
+            public void run() {
+                mActivity.getActiveShell().getContentViewCore().getWindowAndroid().setVSyncPaused(
+                        false);
+            }
+        });
+        mOnTitleUpdatedHelper.waitForCallback(callCount);
+        Assert.assertEquals("2", mTitle);
+    }
+}