[Installed PWA] Waits for a frame swap before hiding a splash screen.

This patch fixes the flash of white between the splash screen and the
web content in installed web apps. This is achieved with waiting for
a compositor frame swap before starting splash screen hiding animation.

Adding callbacks for next frame swap in CompositorViewHolder might not
be at the right level of abstraction - feedback welcome. I introduced
a generic mechanism as we might need it different places as well.
E.g. In CustomTabActivity the same issue is solved with a time delay,
which I plan to change to this mechanism in a follow up patch.

Existing tests for a webapp splash screen cover showing/hiding it in
various circumstances. Writing a specific test to assert flash of white
is fixed would be more work than it's worth it.

FYI: On Google Pixel this causes the splash screen to be shown about
50-100 later, which seems like the time time when flash of white was
visible.

Bug: 734500
Change-Id: I70f8bde54f251c283e260d17a291685738f9e080
Reviewed-on: https://chromium-review.googlesource.com/569552
Commit-Queue: Piotr Swigon <piotrs@chromium.org>
Reviewed-by: Matthew Jones <mdjones@chromium.org>
Reviewed-by: Khushal <khushalsagar@chromium.org>
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487336}

chrome/android/java/src/org/chromium/chrome/browser/compositor/CompositorViewHolder.java

@@ -127,6 +127,9 @@ public class CompositorViewHolder extends FrameLayout
     private int mOverlayContentWidthMeasureSpec = ContentView.DEFAULT_MEASURE_SPEC;
     private int mOverlayContentHeightMeasureSpec = ContentView.DEFAULT_MEASURE_SPEC;
 
+    // List of callbacks to be called on nearest frame swap.
+    private List<Runnable> mNextFrameSwapCallbacks;
+
     /**
      * This view is created on demand to display debugging information.
      */
@@ -598,6 +601,24 @@ public class CompositorViewHolder extends FrameLayout
 
         if (!mSkipInvalidation || pendingFrameCount == 0) flushInvalidation();
         mSkipInvalidation = !mSkipInvalidation;
+
+        runNextFrameSwapCallbacks();
+    }
+
+    /**
+     * @param nextFrameSwapCallback Callback to run on a nearest compositor frame swap.
+     */
+    public void addNextFrameSwapCallback(Runnable nextFrameSwapCallback) {
+        if (mNextFrameSwapCallbacks == null) mNextFrameSwapCallbacks = new ArrayList<>();
+        mNextFrameSwapCallbacks.add(nextFrameSwapCallback);
+    }
+
+    private void runNextFrameSwapCallbacks() {
+        if (mNextFrameSwapCallbacks == null) return;
+        for (Runnable r : mNextFrameSwapCallbacks) {
+            post(r);
+        }
+        mNextFrameSwapCallbacks = null;
     }
 
     @Override

chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappActivity.java

@@ -179,7 +179,7 @@ public class WebappActivity extends SingleTabActivity {
                 controlContainer);
 
         if (getFullscreenManager() != null) getFullscreenManager().setTab(getActivityTab());
-        mSplashController.onFinishedNativeInit(getActivityTab());
+        mSplashController.onFinishedNativeInit(getActivityTab(), getCompositorViewHolder());
         super.finishNativeInitialization();
         mIsInitialized = true;
     }

chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappSplashScreenController.java

@@ -17,6 +17,7 @@ import org.chromium.base.ApiCompatibilityUtils;
 import org.chromium.base.ContextUtils;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.chrome.R;
+import org.chromium.chrome.browser.compositor.CompositorViewHolder;
 import org.chromium.chrome.browser.metrics.WebappUma;
 import org.chromium.chrome.browser.tab.EmptyTabObserver;
 import org.chromium.chrome.browser.tab.Tab;
@@ -24,6 +25,9 @@ import org.chromium.chrome.browser.util.ColorUtils;
 
 /** Shows and hides splash screen. */
 class WebappSplashScreenController extends EmptyTabObserver {
+    /** Used to schedule splash screen hiding. */
+    private CompositorViewHolder mCompositorViewHolder;
+
     /** View to which the splash screen is added. */
     private ViewGroup mParentView;
 
@@ -76,8 +80,9 @@ class WebappSplashScreenController extends EmptyTabObserver {
     }
 
     /** Should be called once native has loaded. */
-    public void onFinishedNativeInit(Tab tab) {
+    public void onFinishedNativeInit(Tab tab, CompositorViewHolder compositorViewHolder) {
         mNativeLoaded = true;
+        mCompositorViewHolder = compositorViewHolder;
         tab.addObserver(this);
         if (mInitializedLayout) {
             mWebappUma.commitMetrics();
@@ -92,27 +97,27 @@ class WebappSplashScreenController extends EmptyTabObserver {
     @Override
     public void didFirstVisuallyNonEmptyPaint(Tab tab) {
         if (canHideSplashScreen()) {
-            hideSplashScreen(tab, WebappUma.SPLASHSCREEN_HIDES_REASON_PAINT);
+            hideSplashScreenOnNextFrameSwap(tab, WebappUma.SPLASHSCREEN_HIDES_REASON_PAINT);
         }
     }
 
     @Override
     public void onPageLoadFinished(Tab tab) {
         if (canHideSplashScreen()) {
-            hideSplashScreen(tab, WebappUma.SPLASHSCREEN_HIDES_REASON_LOAD_FINISHED);
+            hideSplashScreenOnNextFrameSwap(tab, WebappUma.SPLASHSCREEN_HIDES_REASON_LOAD_FINISHED);
         }
     }
 
     @Override
     public void onPageLoadFailed(Tab tab, int errorCode) {
         if (canHideSplashScreen()) {
-            hideSplashScreen(tab, WebappUma.SPLASHSCREEN_HIDES_REASON_LOAD_FAILED);
+            hideSplashScreenOnNextFrameSwap(tab, WebappUma.SPLASHSCREEN_HIDES_REASON_LOAD_FAILED);
         }
     }
 
     @Override
     public void onCrash(Tab tab, boolean sadTabShown) {
-        hideSplashScreen(tab, WebappUma.SPLASHSCREEN_HIDES_REASON_CRASH);
+        hideSplashScreenOnNextFrameSwap(tab, WebappUma.SPLASHSCREEN_HIDES_REASON_CRASH);
     }
 
     protected boolean canHideSplashScreen() {
@@ -181,8 +186,25 @@ class WebappSplashScreenController extends EmptyTabObserver {
         }
     }
 
-    /** Hides the splash screen. */
-    private void hideSplashScreen(final Tab tab, final int reason) {
+    /**
+     * Schedules the splash screen hiding animation once the compositor frame has been swapped.
+     *
+     * Without this callback we were seeing a short flash of white between the splash screen and
+     * the web content (crbug.com/734500).
+     * */
+    private void hideSplashScreenOnNextFrameSwap(final Tab tab, final int reason) {
+        if (mSplashScreen == null || mCompositorViewHolder == null) return;
+
+        mCompositorViewHolder.addNextFrameSwapCallback(new Runnable() {
+            @Override
+            public void run() {
+                animateHidingSplashScreen(tab, reason);
+            }
+        });
+    }
+
+    /** Performs the splash screen hiding animation. */
+    private void animateHidingSplashScreen(final Tab tab, final int reason) {
         if (mSplashScreen == null) return;
 
         mSplashScreen.animate().alpha(0f).withEndAction(new Runnable() {
@@ -192,6 +214,7 @@ class WebappSplashScreenController extends EmptyTabObserver {
                 mParentView.removeView(mSplashScreen);
                 tab.removeObserver(WebappSplashScreenController.this);
                 mSplashScreen = null;
+                mCompositorViewHolder = null;
                 mWebappUma.splashscreenHidden(reason);
             }
         });

chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebApkIntegrationTest.java

@@ -117,7 +117,7 @@ public class WebApkIntegrationTest {
     public void testLaunchAndNavigateOffOrigin() throws Exception {
         startWebApkActivity("org.chromium.webapk.test",
                 mTestServer.getURL("/chrome/test/data/android/test.html"));
-        waitUntilSplashscreenHides();
+        InstrumentationRegistry.getInstrumentation().waitForIdleSync();
 
         // We navigate outside origin and expect Custom Tab to open on top of WebApkActivity.
         mActivityTestRule.runJavaScriptCodeInCurrentTab(