[Instant Start] Create LayoutManager before native is initialized.

The changes of the startup order in this CL are behind the feature flag
"InstantStart".

In this CL, we split setupCompositorContent() into
- setupCompositorContentPreNative() and
- setupCompositorContentPostNative().

The setupCompositorContentPreNative() creates the LayoutManager.

When Instant start is on:
1) triggerLayoutInflation() is called before loading the native library.
2) setupCompositorContentPreNative() is called in
   performPostInflationStartup() before native is initialized.

Besides, the value of field trial "tab_switcher_on_return_time_ms" of
ChromeFeatureList.TAB_SWITCHER_ON_RETURN is cached now.

In the follow up CL, we may move the creation of the LayoutManager into
doLayoutInflation().

Bug: 1041865
Change-Id: Ib1039e152cece799ffed0f636a5e55fafbf4adb2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2110529
Commit-Queue: Xi Han <hanxi@chromium.org>
Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Reviewed-by: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756652}

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/TabUiFeatureUtilities.java

@@ -19,6 +19,7 @@ import org.chromium.chrome.browser.flags.ChromeFeatureList;
 import org.chromium.chrome.browser.flags.DoubleCachedFieldTrialParameter;
 import org.chromium.chrome.browser.flags.IntCachedFieldTrialParameter;
 import org.chromium.chrome.browser.flags.StringCachedFieldTrialParameter;
+import org.chromium.chrome.browser.tasks.ReturnToChromeExperimentsUtil;
 import org.chromium.chrome.features.start_surface.StartSurfaceConfiguration;
 import org.chromium.ui.base.DeviceFormFactor;
 
@@ -44,6 +45,10 @@ public class TabUiFeatureUtilities {
             new StringCachedFieldTrialParameter(ChromeFeatureList.TAB_GRID_LAYOUT_ANDROID,
                     TAB_GRID_LAYOUT_ANDROID_NEW_TAB_TILE_PARAM, "");
 
+    public static final IntCachedFieldTrialParameter TAB_SWITCHER_ON_RETURN_MS =
+            new IntCachedFieldTrialParameter(ChromeFeatureList.TAB_SWITCHER_ON_RETURN,
+                    ReturnToChromeExperimentsUtil.TAB_SWITCHER_ON_RETURN_MS, -1);
+
     public static final String THUMBNAIL_ASPECT_RATIO_PARAM = "thumbnail_aspect_ratio";
     public static final DoubleCachedFieldTrialParameter THUMBNAIL_ASPECT_RATIO =
             new DoubleCachedFieldTrialParameter(

chrome/android/java/src/org/chromium/chrome/browser/ChromeCachedFlags.java

@@ -79,6 +79,7 @@ public class ChromeCachedFlags {
                 TabUiFeatureUtilities.ZOOMING_MIN_SDK,
                 TabUiFeatureUtilities.SKIP_SLOW_ZOOMING,
                 TabUiFeatureUtilities.TAB_GRID_LAYOUT_ANDROID_NEW_TAB_TILE,
+                TabUiFeatureUtilities.TAB_SWITCHER_ON_RETURN_MS,
                 TabUiFeatureUtilities.THUMBNAIL_ASPECT_RATIO);
         // clang-format on
         CachedFeatureFlags.cacheFieldTrialParameters(fieldTrialsToCache);

chrome/android/java/src/org/chromium/chrome/browser/ChromeTabbedActivity.java

@@ -77,6 +77,7 @@ import org.chromium.chrome.browser.download.DownloadUtils;
 import org.chromium.chrome.browser.feed.FeedProcessScopeFactory;
 import org.chromium.chrome.browser.firstrun.FirstRunSignInProcessor;
 import org.chromium.chrome.browser.flags.ActivityType;
+import org.chromium.chrome.browser.flags.CachedFeatureFlags;
 import org.chromium.chrome.browser.flags.ChromeFeatureList;
 import org.chromium.chrome.browser.flags.ChromeSwitches;
 import org.chromium.chrome.browser.fullscreen.ChromeFullscreenManager;
@@ -646,24 +647,48 @@ public class ChromeTabbedActivity
         }
     }
 
-    private void setupCompositorContent() {
-        try (TraceEvent e = TraceEvent.scoped("ChromeTabbedActivity.setupCompositorContent")) {
+    private void setupCompositorContentPreNativeForPhone() {
+        if (isTablet()) return;
+
+        try (TraceEvent e = TraceEvent.scoped(
+                     "ChromeTabbedActivity.setupCompositorContentPreNativeForPhone")) {
             CompositorViewHolder compositorViewHolder = getCompositorViewHolder();
-            if (isTablet()) {
-                mLayoutManager = new LayoutManagerChromeTablet(compositorViewHolder);
-            } else {
-                if (TabUiFeatureUtilities.isGridTabSwitcherEnabled()) {
-                    TabManagementDelegate tabManagementDelegate =
-                            TabManagementModuleProvider.getDelegate();
-                    if (tabManagementDelegate != null) {
-                        mStartSurface = tabManagementDelegate.createStartSurface(this);
-                        assert LibraryLoader.getInstance().isInitialized();
-                        mStartSurface.initWithNative();
-                    }
+            if (TabUiFeatureUtilities.isGridTabSwitcherEnabled()) {
+                TabManagementDelegate tabManagementDelegate =
+                        TabManagementModuleProvider.getDelegate();
+                if (tabManagementDelegate != null) {
+                    mStartSurface = tabManagementDelegate.createStartSurface(this);
+                }
+            }
+            mLayoutManager = new LayoutManagerChromePhone(compositorViewHolder, mStartSurface);
+        }
+    }
+
+    private void setupCompositorContentPreNativeForTablet() {
+        if (!isTablet()) return;
+
+        try (TraceEvent e = TraceEvent.scoped(
+                     "ChromeTabbedActivity.setupCompositorContentPreNativeForTablet")) {
+            mLayoutManager = new LayoutManagerChromeTablet(getCompositorViewHolder());
+        }
+    }
+
+    private void setupCompositorContentPostNative() {
+        try (TraceEvent e = TraceEvent.scoped(
+                     "ChromeTabbedActivity.setupCompositorContentPostNative")) {
+            if (!isLayoutManagerCreated()) {
+                if (isTablet()) {
+                    setupCompositorContentPreNativeForTablet();
+                } else {
+                    setupCompositorContentPreNativeForPhone();
                 }
+            }
 
-                mLayoutManager = new LayoutManagerChromePhone(compositorViewHolder, mStartSurface);
+            if (mStartSurface != null) {
+                assert LibraryLoader.getInstance().isInitialized();
+                mStartSurface.initWithNative();
             }
+
             mLayoutManager.setEnableAnimations(DeviceClassManager.enableAnimations());
 
             // TODO(yusufo): get rid of findViewById(R.id.url_bar).
@@ -674,6 +699,10 @@ public class ChromeTabbedActivity
         }
     }
 
+    private boolean isLayoutManagerCreated() {
+        return mLayoutManager != null;
+    }
+
     private void initializeToolbarManager() {
         try (TraceEvent e = TraceEvent.scoped("ChromeTabbedActivity.initializeToolbarManager")) {
             mUndoBarPopupController.initialize();
@@ -780,8 +809,9 @@ public class ChromeTabbedActivity
         }
     }
 
-    private void addOverviewModeObserver() {
-        try (TraceEvent e = TraceEvent.scoped("ChromeTabbedActivity.addOverviewModeObserver")) {
+    private void addOverviewModeObserverPreNative() {
+        try (TraceEvent e = TraceEvent.scoped(
+                     "ChromeTabbedActivity.addOverviewModeObserverPreNative")) {
             mOverviewModeController.overrideOverviewModeController(mLayoutManager);
             mOverviewModeObserver = new EmptyOverviewModeObserver() {
                 @Override
@@ -799,6 +829,15 @@ public class ChromeTabbedActivity
                 }
             };
             mOverviewModeController.addOverviewModeObserver(mOverviewModeObserver);
+        }
+    }
+
+    private void addOverviewModeObserverPostNative() {
+        try (TraceEvent e = TraceEvent.scoped(
+                     "ChromeTabbedActivity.addOverviewModeObserverPostNative")) {
+            if (mOverviewModeObserver == null) {
+                addOverviewModeObserverPreNative();
+            }
 
             if (ChromeFeatureList.isEnabled(ChromeFeatureList.TAB_ENGAGEMENT_REPORTING_ANDROID)) {
                 // The lifecycle of this object is managed by the lifecycle dispatcher.
@@ -837,7 +876,7 @@ public class ChromeTabbedActivity
                         ChromeFeatureList.DARKEN_WEBSITES_CHECKBOX_IN_THEMES_SETTING)) {
                 WebContentsDarkModeController.createInstance();
             }
-            setupCompositorContent();
+            setupCompositorContentPostNative();
 
             // All this initialization can be expensive so it's split into multiple tasks.
             PostTask.postTask(UiThreadTaskTraits.DEFAULT, this::refreshSignIn);
@@ -849,7 +888,7 @@ public class ChromeTabbedActivity
 
             PostTask.postTask(UiThreadTaskTraits.DEFAULT,
                     this::maybeGetFeedAppLifecycleAndMaybeCreatePageViewObserver);
-            PostTask.postTask(UiThreadTaskTraits.DEFAULT, this::addOverviewModeObserver);
+            PostTask.postTask(UiThreadTaskTraits.DEFAULT, this::addOverviewModeObserverPostNative);
             PostTask.postTask(UiThreadTaskTraits.DEFAULT, this::finishNativeInitialization);
             AccessibilityUtil.addObserver(this);
         }
@@ -1527,6 +1566,24 @@ public class ChromeTabbedActivity
 
         mUndoBarPopupController =
                 new UndoBarController(this, mTabModelSelectorImpl, this::getSnackbarManager);
+
+        // When the feature flag {@link ChromeFeatureList.INSTANT_START} turns on phones (not
+        // tablet), a view-only start page created on Java will be shown before native is
+        // initialized.
+        if (CachedFeatureFlags.isEnabled(ChromeFeatureList.INSTANT_START) && !isTablet()) {
+            prepareToShowStartPagePreNative();
+        }
+    }
+
+    /**
+     * Prepares to show the start page before native is initialized. For example, create
+     * an LayoutManagerChrome object, add overview mode observer and so on.
+     */
+    private void prepareToShowStartPagePreNative() {
+        setupCompositorContentPreNativeForPhone();
+        getCompositorViewHolder().setLayoutManager(mLayoutManager);
+        mLayoutManager.setTabModelSelector(mTabModelSelectorImpl);
+        addOverviewModeObserverPreNative();
     }
 
     @Override

chrome/android/java/src/org/chromium/chrome/browser/init/AsyncInitializationActivity.java

@@ -38,6 +38,8 @@ import org.chromium.chrome.browser.IntentHandler;
 import org.chromium.chrome.browser.LaunchIntentDispatcher;
 import org.chromium.chrome.browser.WarmupManager;
 import org.chromium.chrome.browser.firstrun.FirstRunFlowSequencer;
+import org.chromium.chrome.browser.flags.CachedFeatureFlags;
+import org.chromium.chrome.browser.flags.ChromeFeatureList;
 import org.chromium.chrome.browser.lifecycle.ActivityLifecycleDispatcher;
 import org.chromium.chrome.browser.multiwindow.MultiWindowModeStateDispatcher;
 import org.chromium.chrome.browser.multiwindow.MultiWindowModeStateDispatcherImpl;
@@ -154,18 +156,27 @@ public abstract class AsyncInitializationActivity extends ChromeBaseAppCompatAct
 
     @Override
     public final void setContentViewAndLoadLibrary(Runnable onInflationCompleteCallback) {
-        // Start loading libraries before triggerLayoutInflation(). This "hides" library loading
-        // behind UI inflation and prevents stalling UI thread. See https://crbug.com/796957 for
-        // details. Note that for optimal performance AsyncInitTaskRunner.startBackgroundTasks()
-        // needs to start warmup renderer only after library is loaded.
+        boolean enableInstantStart = CachedFeatureFlags.isEnabled(ChromeFeatureList.INSTANT_START);
+        mOnInflationCompleteCallback = onInflationCompleteCallback;
+        if (enableInstantStart) {
+            triggerLayoutInflation();
+        }
+
+        // Start loading libraries. It happens before triggerLayoutInflation() for regular startup,
+        // but after triggerLayoutInflation() for instant start because we prioritize a Java UI and
+        // not rendering web content. This "hides" library loading behind UI inflation and prevents
+        // stalling UI thread. See https://crbug.com/796957 for details. Note that for optimal
+        // performance AsyncInitTaskRunner.startBackgroundTasks() needs to start warmup renderer
+        // only after library is loaded.
 
         if (!mStartupDelayed) {
             // Kick off long running IO tasks that can be done in parallel.
             mNativeInitializationController.startBackgroundTasks(shouldAllocateChildConnection());
         }
 
-        mOnInflationCompleteCallback = onInflationCompleteCallback;
-        triggerLayoutInflation();
+        if (!enableInstantStart) {
+            triggerLayoutInflation();
+        }
         if (mLaunchBehindWorkaround != null) mLaunchBehindWorkaround.onSetContentView();
     }
 

chrome/android/java/src/org/chromium/chrome/browser/tasks/ReturnToChromeExperimentsUtil.java

@@ -15,12 +15,12 @@ import org.chromium.base.Log;
 import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.base.metrics.RecordUserAction;
 import org.chromium.chrome.browser.ChromeActivity;
-import org.chromium.chrome.browser.flags.ChromeFeatureList;
 import org.chromium.chrome.browser.homepage.HomepageManager;
 import org.chromium.chrome.browser.locale.LocaleManager;
 import org.chromium.chrome.browser.ntp.NewTabPage;
 import org.chromium.chrome.browser.tab.TabLaunchType;
 import org.chromium.chrome.browser.tabmodel.TabModel;
+import org.chromium.chrome.browser.tasks.tab_management.TabUiFeatureUtilities;
 import org.chromium.chrome.browser.util.AccessibilityUtil;
 import org.chromium.chrome.features.start_surface.StartSurfaceConfiguration;
 import org.chromium.content_public.browser.LoadUrlParams;
@@ -34,7 +34,7 @@ public final class ReturnToChromeExperimentsUtil {
     private static final String TAG = "TabSwitcherOnReturn";
 
     @VisibleForTesting
-    static final String TAB_SWITCHER_ON_RETURN_MS = "tab_switcher_on_return_time_ms";
+    public static final String TAB_SWITCHER_ON_RETURN_MS = "tab_switcher_on_return_time_ms";
 
     @VisibleForTesting
     static final String UMA_TIME_TO_GTS_FIRST_MEANINGFUL_PAINT =
@@ -57,8 +57,7 @@ public final class ReturnToChromeExperimentsUtil {
      * @return true if past threshold, false if not past threshold or experiment cannot be loaded.
      */
     public static boolean shouldShowTabSwitcher(final long lastBackgroundedTimeMillis) {
-        int tabSwitcherAfterMillis = ChromeFeatureList.getFieldTrialParamByFeatureAsInt(
-                ChromeFeatureList.TAB_SWITCHER_ON_RETURN, TAB_SWITCHER_ON_RETURN_MS, -1);
+        int tabSwitcherAfterMillis = TabUiFeatureUtilities.TAB_SWITCHER_ON_RETURN_MS.getValue();
 
         if (lastBackgroundedTimeMillis == -1) {
             // No last background timestamp set, use control behavior unless "immediate" was set.

chrome/android/javatests/src/org/chromium/chrome/browser/InstantStartTest.java

@@ -4,6 +4,8 @@
 
 package org.chromium.chrome.browser;
 
+import static com.google.common.truth.Truth.assertThat;
+
 import android.content.Intent;
 import android.graphics.Bitmap;
 import android.support.test.filters.SmallTest;
@@ -18,13 +20,22 @@ import org.junit.runner.RunWith;
 import org.chromium.base.Callback;
 import org.chromium.base.library_loader.LibraryLoader;
 import org.chromium.base.test.util.CommandLineFlags;
+import org.chromium.base.test.util.Matchers;
+import org.chromium.base.test.util.Restriction;
+import org.chromium.chrome.browser.compositor.layouts.LayoutManagerChromePhone;
+import org.chromium.chrome.browser.compositor.layouts.LayoutManagerChromeTablet;
 import org.chromium.chrome.browser.compositor.layouts.content.TabContentManager;
+import org.chromium.chrome.browser.flags.CachedFeatureFlags;
+import org.chromium.chrome.browser.flags.ChromeFeatureList;
 import org.chromium.chrome.browser.flags.ChromeSwitches;
+import org.chromium.chrome.browser.tasks.ReturnToChromeExperimentsUtil;
+import org.chromium.chrome.features.start_surface.StartSurfaceLayout;
 import org.chromium.chrome.test.ChromeJUnit4ClassRunner;
 import org.chromium.chrome.test.ChromeTabbedActivityTestRule;
 import org.chromium.chrome.test.util.browser.Features;
 import org.chromium.content_public.browser.test.util.Criteria;
 import org.chromium.content_public.browser.test.util.CriteriaHelper;
+import org.chromium.ui.test.util.UiRestriction;
 
 import java.io.File;
 import java.io.FileNotFoundException;
@@ -35,8 +46,14 @@ import java.io.IOException;
  * Integration tests of Instant Start which requires 2-stage initialization for Clank startup.
  */
 @RunWith(ChromeJUnit4ClassRunner.class)
+// clang-format off
 @CommandLineFlags.Add({ChromeSwitches.DISABLE_FIRST_RUN_EXPERIENCE})
+@Features.EnableFeatures({ChromeFeatureList.TAB_GRID_LAYOUT_ANDROID,
+        ChromeFeatureList.START_SURFACE_ANDROID, ChromeFeatureList.INSTANT_START})
 public class InstantStartTest {
+    // clang-format on
+    private static final String IMMEDIATE_RETURN_PARAMS = "force-fieldtrial-params=Study.Group:"
+            + ReturnToChromeExperimentsUtil.TAB_SWITCHER_ON_RETURN_MS + "/0";
     private Bitmap mBitmap;
     private int mThumbnailFetchCount;
 
@@ -48,20 +65,15 @@ public class InstantStartTest {
 
     @Before
     public void setUp() {
-        startMainActivityFromLauncherAndNotWaitForNative();
+        startMainActivityFromLauncher();
     }
 
-    private void startMainActivityFromLauncherAndNotWaitForNative() {
+    private void startMainActivityFromLauncher() {
         // Only launch Chrome.
         Intent intent = new Intent(Intent.ACTION_MAIN);
         intent.addCategory(Intent.CATEGORY_LAUNCHER);
         mActivityTestRule.prepareUrlIntent(intent, null);
         mActivityTestRule.startActivityCompletely(intent);
-
-        CriteriaHelper.pollUiThread(
-                ()
-                        -> mActivityTestRule.getActivity().getTabContentManager() != null,
-                "TabContentManager never created.");
     }
 
     private Bitmap createThumbnailBitmapAndWriteToFile(int tabId) {
@@ -101,6 +113,12 @@ public class InstantStartTest {
             mThumbnailFetchCount++;
             mBitmap = bitmap;
         };
+
+        CriteriaHelper.pollUiThread(Criteria.checkThat(
+                ()
+                        -> mActivityTestRule.getActivity().getTabContentManager(),
+                Matchers.notNullValue()));
+
         TabContentManager tabContentManager =
                 mActivityTestRule.getActivity().getTabContentManager();
 
@@ -120,4 +138,42 @@ public class InstantStartTest {
         Assert.assertEquals(thumbnailBitmap.getWidth(), fetchedThumbnail.getWidth());
         Assert.assertEquals(thumbnailBitmap.getHeight(), fetchedThumbnail.getHeight());
     }
+
+    @Test
+    @SmallTest
+    // clang-format off
+    @CommandLineFlags.Add({ChromeSwitches.DISABLE_NATIVE_INITIALIZATION,
+            "enable-features=" + ChromeFeatureList.TAB_SWITCHER_ON_RETURN + "<Study",
+            "force-fieldtrials=Study/Group", IMMEDIATE_RETURN_PARAMS})
+    @Restriction({UiRestriction.RESTRICTION_TYPE_PHONE})
+    public void layoutManagerChromePhonePreNativeTest() {
+        // clang-format on
+        Assert.assertFalse(mActivityTestRule.getActivity().isTablet());
+        Assert.assertTrue(CachedFeatureFlags.isEnabled(ChromeFeatureList.INSTANT_START));
+        Assert.assertTrue(ReturnToChromeExperimentsUtil.shouldShowTabSwitcher(-1));
+
+        CriteriaHelper.pollUiThread(Criteria.checkThat(
+                () -> mActivityTestRule.getActivity().getLayoutManager(), Matchers.notNullValue()));
+
+        Assert.assertFalse(LibraryLoader.getInstance().isInitialized());
+        assertThat(mActivityTestRule.getActivity().getLayoutManager())
+                .isInstanceOf(LayoutManagerChromePhone.class);
+        assertThat(mActivityTestRule.getActivity().getLayoutManager().getOverviewLayout())
+                .isInstanceOf(StartSurfaceLayout.class);
+    }
+
+    @Test
+    @SmallTest
+    @Restriction({UiRestriction.RESTRICTION_TYPE_TABLET})
+    public void willInitNativeOnTabletTest() {
+        Assert.assertTrue(mActivityTestRule.getActivity().isTablet());
+        Assert.assertTrue(CachedFeatureFlags.isEnabled(ChromeFeatureList.INSTANT_START));
+
+        CriteriaHelper.pollUiThread(Criteria.checkThat(
+                () -> mActivityTestRule.getActivity().getLayoutManager(), Matchers.notNullValue()));
+
+        Assert.assertTrue(LibraryLoader.getInstance().isInitialized());
+        assertThat(mActivityTestRule.getActivity().getLayoutManager())
+                .isInstanceOf(LayoutManagerChromeTablet.class);
+    }
 }
\ No newline at end of file