Resume native init in InstantStartTest

After pre-native tests, resume native initialization and make sure the
test doesn't crash.

Bug: 1065314
Change-Id: I0ecf3b4b5b9925169f35f1b719671f0d0faa0750
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2143611Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Reviewed-by: Xi Han <hanxi@chromium.org>
Commit-Queue: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#760725}

chrome/android/features/start_surface/internal/javatests/src/org/chromium/chrome/features/start_surface/InstantStartTest.java

@@ -22,6 +22,7 @@ import org.junit.rules.TestRule;
 import org.junit.runner.RunWith;
 
 import org.chromium.base.Callback;
+import org.chromium.base.CommandLine;
 import org.chromium.base.library_loader.LibraryLoader;
 import org.chromium.base.test.util.CommandLineFlags;
 import org.chromium.base.test.util.Feature;
@@ -307,6 +308,31 @@ public class InstantStartTest {
                 Criteria.equals(true, () -> allCardsHaveThumbnail(recyclerView)));
         mRenderTestRule.render(mActivityTestRule.getActivity().findViewById(R.id.tab_list_view),
                 "tabSwitcher_3tabs");
+
+        // Resume native initialization and make sure it doesn't crash.
+        // TODO(crbug.com/1065314): emulate realistic pre-native to post-native transition
+        //  with real tab models, and make sure the GTS looks the same.
+        //  Right now the real tab model is empty despite of our fake state file.
+        Assert.assertFalse(LibraryLoader.getInstance().isInitialized());
+
+        CommandLine.getInstance().removeSwitch(ChromeSwitches.DISABLE_NATIVE_INITIALIZATION);
+        TestThreadUtils.runOnUiThreadBlocking(
+                () -> mActivityTestRule.getActivity().startDelayedNativeInitializationForTests());
+        CriteriaHelper.pollUiThread(() -> {
+            return mActivityTestRule.getActivity()
+                            .getTabModelSelector()
+                            .getTabModelFilterProvider()
+                            .getCurrentTabModelFilter()
+                    != null
+                    && mActivityTestRule.getActivity()
+                               .getTabModelSelector()
+                               .getTabModelFilterProvider()
+                               .getCurrentTabModelFilter()
+                               .isTabModelRestored();
+        });
+        Assert.assertTrue(LibraryLoader.getInstance().isInitialized());
+        mRenderTestRule.render(mActivityTestRule.getActivity().findViewById(R.id.tab_list_view),
+                "tabSwitcher_empty");
     }
 
     @Test

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

@@ -325,7 +325,22 @@ class TabSwitcherMediator implements TabSwitcher.Controller, TabListRecyclerView
 
         mFullscreenManager.addListener(mFullscreenListener);
 
-        if (!mTabModelSelector.getModels().isEmpty()) {
+        if (mTabModelSelector.getModels().isEmpty()) {
+            TabModelSelectorObserver selectorObserver = new EmptyTabModelSelectorObserver() {
+                @Override
+                public void onChange() {
+                    assert !mTabModelSelector.getModels().isEmpty();
+                    assert mTabModelSelector.getTabModelFilterProvider().getTabModelFilter(false)
+                            != null;
+                    assert mTabModelSelector.getTabModelFilterProvider().getTabModelFilter(true)
+                            != null;
+                    mTabModelSelector.removeObserver(this);
+                    mTabModelSelector.getTabModelFilterProvider().addTabModelFilterObserver(
+                            mTabModelObserver);
+                }
+            };
+            mTabModelSelector.addObserver(selectorObserver);
+        } else {
             mTabModelSelector.getTabModelFilterProvider().addTabModelFilterObserver(
                     mTabModelObserver);
         }

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

@@ -374,6 +374,12 @@ public abstract class AsyncInitializationActivity extends ChromeBaseAppCompatAct
         if (mFirstDrawComplete) onFirstDrawComplete();
     }
 
+    @VisibleForTesting
+    public void startDelayedNativeInitializationForTests() {
+        mStartupDelayed = true;
+        startDelayedNativeInitialization();
+    }
+
     /**
      * @return Whether the native library initialization is delayed at this point.
      */