Migrate first run dialog to viewpager2

The motivation for the migration is that FragmentStatePagerAdapter is
deprecated.

BUG=1162839

Change-Id: I600ef392633b9c75cf1b11a6e56a862a685f7c6f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2611949
Commit-Queue: Peter Kotwicz <pkotwicz@chromium.org>
Reviewed-by: Sky Malice <skym@chromium.org>
Reviewed-by: Wenyu Fu <wenyufu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843402}

chrome/android/chrome_java_sources.gni

@@ -611,7 +611,6 @@ chrome_java_sources = [
   "java/src/org/chromium/chrome/browser/firstrun/FirstRunStatus.java",
   "java/src/org/chromium/chrome/browser/firstrun/FirstRunUtils.java",
   "java/src/org/chromium/chrome/browser/firstrun/FirstRunView.java",
-  "java/src/org/chromium/chrome/browser/firstrun/FirstRunViewPager.java",
   "java/src/org/chromium/chrome/browser/firstrun/ForcedSigninProcessor.java",
   "java/src/org/chromium/chrome/browser/firstrun/FreIntentCreator.java",
   "java/src/org/chromium/chrome/browser/firstrun/LightweightFirstRunActivity.java",

chrome/android/expectations/lint-baseline.xml

@@ -1640,17 +1640,6 @@
             column="9"/>
     </issue>
 
-    <issue
-        id="ClickableViewAccessibility"
-        message="Custom view `FirstRunViewPager` overrides `onTouchEvent` but not `performClick`"
-        errorLine1="    public boolean onTouchEvent(MotionEvent event) {"
-        errorLine2="                   ~~~~~~~~~~~~">
-        <location
-            file="../../chrome/android/java/src/org/chromium/chrome/browser/firstrun/FirstRunViewPager.java"
-            line="21"
-            column="20"/>
-    </issue>
-
     <issue
         id="ClickableViewAccessibility"
         message="Custom view ``EditText`` has `setOnTouchListener` called on it but does not override `performClick`"

chrome/android/java/src/org/chromium/chrome/browser/firstrun/FirstRunActivity.java

@@ -14,6 +14,7 @@ import androidx.annotation.CallSuper;
 import androidx.annotation.StringRes;
 import androidx.annotation.VisibleForTesting;
 import androidx.fragment.app.Fragment;
+import androidx.viewpager2.widget.ViewPager2;
 
 import org.chromium.base.ActivityState;
 import org.chromium.base.ApplicationStatus;
@@ -96,8 +97,6 @@ public class FirstRunActivity extends FirstRunActivityBase implements FirstRunPa
     private Set<FirstRunFragment> mPagesToNotifyOfNativeInit;
     private boolean mDeferredCompleteFRE;
 
-    private FirstRunViewPager mPager;
-
     private FirstRunFlowSequencer mFirstRunFlowSequencer;
 
     private Bundle mFreProperties;
@@ -118,6 +117,8 @@ public class FirstRunActivity extends FirstRunActivityBase implements FirstRunPa
     private final List<FirstRunPage> mPages = new ArrayList<>();
     private final List<Integer> mFreProgressStates = new ArrayList<>();
 
+    private ViewPager2 mPager;
+
     /**
      * The pager adapter, which provides the pages to the view pager widget.
      */
@@ -204,7 +205,11 @@ public class FirstRunActivity extends FirstRunActivityBase implements FirstRunPa
      */
     @CallSuper
     protected View createContentView() {
-        mPager = new FirstRunViewPager(this);
+        mPager = new ViewPager2(this);
+
+        // Disable swipe gesture.
+        mPager.setUserInputEnabled(false);
+
         mPager.setId(R.id.fre_pager);
         mPager.setOffscreenPageLimit(3);
         return mPager;
@@ -245,8 +250,7 @@ public class FirstRunActivity extends FirstRunActivityBase implements FirstRunPa
                     return;
                 }
 
-                mPagerAdapter = new FirstRunPagerAdapter(getSupportFragmentManager(), mPages);
-                stopProgressionIfNotAcceptedTermsOfService();
+                mPagerAdapter = new FirstRunPagerAdapter(FirstRunActivity.this, mPages);
                 mPager.setAdapter(mPagerAdapter);
 
                 if (areNativeAndPoliciesInitialized()) {
@@ -369,7 +373,6 @@ public class FirstRunActivity extends FirstRunActivityBase implements FirstRunPa
     @Override
     public void onStart() {
         super.onStart();
-        stopProgressionIfNotAcceptedTermsOfService();
     }
 
     @Override
@@ -380,12 +383,6 @@ public class FirstRunActivity extends FirstRunActivityBase implements FirstRunPa
             return;
         }
 
-        Object currentItem = mPagerAdapter.instantiateItem(mPager, mPager.getCurrentItem());
-        if (currentItem instanceof FirstRunFragment) {
-            FirstRunFragment page = (FirstRunFragment) currentItem;
-            if (page.interceptBackPressed()) return;
-        }
-
         if (mPager.getCurrentItem() == 0) {
             abortFirstRunExperience();
         } else {
@@ -522,7 +519,6 @@ public class FirstRunActivity extends FirstRunActivityBase implements FirstRunPa
         FirstRunUtils.acceptTermsOfService(allowCrashUpload);
         FirstRunStatus.setSkipWelcomePage(true);
         flushPersistentData();
-        stopProgressionIfNotAcceptedTermsOfService();
         jumpToPage(mPager.getCurrentItem() + 1);
     }
 
@@ -557,7 +553,7 @@ public class FirstRunActivity extends FirstRunActivityBase implements FirstRunPa
     }
 
     private boolean setCurrentItemForPager(int position) {
-        if (position >= mPagerAdapter.getCount()) {
+        if (position >= mPagerAdapter.getItemCount()) {
             completeFirstRunExperience();
             return false;
         }
@@ -565,26 +561,14 @@ public class FirstRunActivity extends FirstRunActivityBase implements FirstRunPa
         mPager.setCurrentItem(position, false);
 
         // Set A11y focus if possible. See https://crbug.com/1094064 for more context.
-        // * Screen reader can lose focus when switching between pages with ViewPager;
-        // * FragmentPagerStateAdapter is trying to limit access for the real fragment that we are
-        // creating / created;
-        // * Note that despite the function name and javadoc,
-        // FragmentPagerStateAdapter#instantiateItem returns cached fragments when possible. This
-        // should always be the case here as ViewPager#setCurrentItem will trigger instantiation if
-        // needed. This function call to #instantiateItem is not creating new fragment here but
-        // rather reading the ones already created.
-        Object currentFragment = mPagerAdapter.instantiateItem(mPager, position);
-        if (currentFragment instanceof FirstRunFragment) {
-            ((FirstRunFragment) currentFragment).setInitialA11yFocus();
+        // The screen reader can lose focus when switching between pages with ViewPager2.
+        FirstRunFragment currentFragment = mPagerAdapter.getFirstRunFragment(position);
+        if (currentFragment != null) {
+            currentFragment.setInitialA11yFocus();
         }
         return true;
     }
 
-    private void stopProgressionIfNotAcceptedTermsOfService() {
-        if (mPagerAdapter == null) return;
-        mPagerAdapter.setStopAtTheFirstPage(!didAcceptTermsOfService());
-    }
-
     private void skipPagesIfNecessary() {
         if (mPagerAdapter == null) return;
 

chrome/android/java/src/org/chromium/chrome/browser/firstrun/FirstRunFragment.java

@@ -15,13 +15,6 @@ public interface FirstRunFragment {
      */
     default void onNativeInitialized() {}
 
-    /**
-     * @return Whether the back button press was handled by this page.
-     */
-    default boolean interceptBackPressed() {
-        return false;
-    }
-
     /**
      * @see Fragment#getActivity().
      */

chrome/android/java/src/org/chromium/chrome/browser/firstrun/FirstRunPagerAdapter.java

@@ -5,46 +5,53 @@
 package org.chromium.chrome.browser.firstrun;
 
 import androidx.fragment.app.Fragment;
-import androidx.fragment.app.FragmentManager;
-import androidx.fragment.app.FragmentStatePagerAdapter;
+import androidx.fragment.app.FragmentActivity;
+import androidx.viewpager2.adapter.FragmentStateAdapter;
 
+import java.util.ArrayList;
 import java.util.List;
 
 /**
  * Adapter used to provide First Run pages to the FirstRunActivity ViewPager.
  */
-class FirstRunPagerAdapter extends FragmentStatePagerAdapter {
+class FirstRunPagerAdapter extends FragmentStateAdapter {
     private final List<FirstRunPage> mPages;
 
-    private boolean mStopAtTheFirstPage;
+    private final List<FirstRunFragment> mFragments = new ArrayList<>();
 
-    public FirstRunPagerAdapter(FragmentManager fragmentManager, List<FirstRunPage> pages) {
-        super(fragmentManager);
+    public FirstRunPagerAdapter(FragmentActivity activity, List<FirstRunPage> pages) {
+        super(activity);
         assert pages != null;
         assert pages.size() > 0;
         mPages = pages;
     }
 
     /**
-     * Controls progression beyond the first page.
-     * @param stop True if no progression beyond the first page is allowed.
+     * Returns the FirstRunFragment at the passed-in position. Returns null if the fragment has not
+     * yet been instantiated by RecyclerView.
      */
-    void setStopAtTheFirstPage(boolean stop) {
-        if (stop != mStopAtTheFirstPage) {
-            mStopAtTheFirstPage = stop;
-            notifyDataSetChanged();
-        }
+    public FirstRunFragment getFirstRunFragment(int position) {
+        return (position < mFragments.size()) ? mFragments.get(position) : null;
     }
 
     @Override
-    public Fragment getItem(int position) {
+    public Fragment createFragment(int position) {
         assert position >= 0 && position < mPages.size();
-        return mPages.get(position).instantiateFragment();
+        Fragment fragment = mPages.get(position).instantiateFragment();
+
+        for (int i = mFragments.size(); i <= position; i++) {
+            mFragments.add(null);
+        }
+
+        // Caching fragment is OK because FirstRunActivity retains all of the fragments via
+        // ViewPager2#setOffscreenPageLimit(). See crbug.com/740897 for details.
+        mFragments.set(position, (FirstRunFragment) fragment);
+
+        return fragment;
     }
 
     @Override
-    public int getCount() {
-        if (mStopAtTheFirstPage) return 1;
+    public int getItemCount() {
         return mPages.size();
     }
 }

chrome/android/java/src/org/chromium/chrome/browser/firstrun/FirstRunViewPager.java

-// Copyright 2016 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.chrome.browser.firstrun;
-
-import android.content.Context;
-import android.view.MotionEvent;
-
-import androidx.viewpager.widget.ViewPager;
-
-/**
-* ViewPager without swipe gesture.
-*/
-public class FirstRunViewPager extends ViewPager {
-    FirstRunViewPager(Context context) {
-        super(context);
-    }
-
-    @Override
-    public boolean onTouchEvent(MotionEvent event) {
-        return false;
-    }
-
-    @Override
-    public boolean onInterceptTouchEvent(MotionEvent event) {
-        return false;
-    }
-}