[Feed] Handle supervised user/enterprise policy on Feed NTP

Use a ScrollView instead of the Stream for the NTP if supervised
user or enterprise policy is enabled.

Bug: 862832
Change-Id: I8987db14dac17ef525860817fcc341b254fea358
Reviewed-on: https://chromium-review.googlesource.com/1208814
Commit-Queue: Becky Zhou <huayinz@chromium.org>
Reviewed-by: Theresa <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589609}

chrome/android/feed/core/java/src/org/chromium/chrome/browser/feed/FeedNewTabPageMediator.java

@@ -5,6 +5,8 @@
 package org.chromium.chrome.browser.feed;
 
 import android.content.res.Resources;
+import android.graphics.Rect;
+import android.widget.ScrollView;
 
 import com.google.android.libraries.feed.api.stream.ContentChangedListener;
 import com.google.android.libraries.feed.api.stream.ScrollListener;
@@ -36,6 +38,7 @@ class FeedNewTabPageMediator
     private SectionHeader mSectionHeader;
     private MemoryPressureCallback mMemoryPressureCallback;
 
+    private boolean mFeedEnabled;
     private boolean mTouchEnabled = true;
     private boolean mStreamContentChanged;
     private int mThumbnailWidth;
@@ -44,31 +47,26 @@ class FeedNewTabPageMediator
 
     /**
      * @param feedNewTabPage The {@link FeedNewTabPage} that interacts with this class.
+     * @param snapScrollHelper The {@link SnapScrollHelper} that handles snap scrolling.
      */
     FeedNewTabPageMediator(FeedNewTabPage feedNewTabPage, SnapScrollHelper snapScrollHelper) {
         mCoordinator = feedNewTabPage;
         mSnapScrollHelper = snapScrollHelper;
-        initializeProperties();
 
         mPrefChangeRegistrar = new PrefChangeRegistrar();
-        mPrefChangeRegistrar.addObserver(
-                Pref.NTP_ARTICLES_LIST_VISIBLE, this::updateSectionHeader);
+        mPrefChangeRegistrar.addObserver(Pref.NTP_ARTICLES_SECTION_ENABLED, this::updateContent);
+        initialize();
+        // Create the content.
+        updateContent();
     }
 
     /** Clears any dependencies. */
     void destroy() {
-        Stream stream = mCoordinator.getStream();
-        stream.removeScrollListener(mStreamScrollListener);
-        stream.removeOnContentChangedListener(mStreamContentChangedListener);
+        destroyPropertiesForStream();
         mPrefChangeRegistrar.destroy();
-        MemoryPressureListener.removeCallback(mMemoryPressureCallback);
     }
 
-    /**
-     * Initialize properties for UI components in the {@link FeedNewTabPage}.
-     * TODO(huayinz): Introduce a Model for these properties.
-     */
-    private void initializeProperties() {
+    private void initialize() {
         // Listen for layout changes on the NewTabPageView itself to catch changes in scroll
         // position that are due to layout changes after e.g. device rotation. This contrasts with
         // regular scrolling, which is observed through an OnScrollListener.
@@ -76,7 +74,33 @@ class FeedNewTabPageMediator
                 (v, left, top, right, bottom, oldLeft, oldTop, oldRight, oldBottom) -> {
                     mSnapScrollHelper.handleScroll();
                 });
+    }
+
+    /** Update the content based on supervised user or enterprise policy. */
+    private void updateContent() {
+        mFeedEnabled =
+                PrefServiceBridge.getInstance().getBoolean(Pref.NTP_ARTICLES_SECTION_ENABLED);
+        if ((mFeedEnabled && mCoordinator.getStream() != null)
+                || (!mFeedEnabled && mCoordinator.getScrollViewForPolicy() != null))
+            return;
+
+        if (mFeedEnabled) {
+            mCoordinator.createStream();
+            mSnapScrollHelper.setView(mCoordinator.getStream().getView());
+            initializePropertiesForStream();
+        } else {
+            destroyPropertiesForStream();
+            mCoordinator.createScrollViewForPolicy();
+            mSnapScrollHelper.setView(mCoordinator.getScrollViewForPolicy());
+            initializePropertiesForPolicy();
+        }
+    }
 
+    /**
+     * Initialize properties for UI components in the {@link FeedNewTabPage}.
+     * TODO(huayinz): Introduce a Model for these properties.
+     */
+    private void initializePropertiesForStream() {
         Stream stream = mCoordinator.getStream();
         mStreamScrollListener = new ScrollListener() {
             @Override
@@ -97,6 +121,8 @@ class FeedNewTabPageMediator
                 new SectionHeader(res.getString(R.string.ntp_article_suggestions_section_header),
                         PrefServiceBridge.getInstance().getBoolean(Pref.NTP_ARTICLES_LIST_VISIBLE),
                         this::onSectionHeaderToggled);
+        mPrefChangeRegistrar.addObserver(
+                Pref.NTP_ARTICLES_LIST_VISIBLE, this::updateSectionHeader);
         mCoordinator.getSectionHeaderView().setHeader(mSectionHeader);
         stream.setStreamContentVisibility(mSectionHeader.isExpanded());
 
@@ -104,6 +130,28 @@ class FeedNewTabPageMediator
         MemoryPressureListener.addCallback(mMemoryPressureCallback);
     }
 
+    /** Clear any dependencies related to the {@link Stream}. */
+    private void destroyPropertiesForStream() {
+        Stream stream = mCoordinator.getStream();
+        if (stream == null) return;
+
+        stream.removeScrollListener(mStreamScrollListener);
+        stream.removeOnContentChangedListener(mStreamContentChangedListener);
+        MemoryPressureListener.removeCallback(mMemoryPressureCallback);
+        mPrefChangeRegistrar.removeObserver(Pref.NTP_ARTICLES_LIST_VISIBLE);
+        mStreamScrollListener = null;
+        mStreamContentChangedListener = null;
+        mMemoryPressureCallback = null;
+    }
+
+    /**
+     * Initialize properties for the scroll view shown under supervised user or enterprise policy.
+     */
+    private void initializePropertiesForPolicy() {
+        ScrollView view = mCoordinator.getScrollViewForPolicy();
+        view.getViewTreeObserver().addOnScrollChangedListener(mSnapScrollHelper::handleScroll);
+    }
+
     /** Update whether the section header should be expanded. */
     private void updateSectionHeader() {
         if (mSectionHeader.isExpanded()
@@ -158,26 +206,42 @@ class FeedNewTabPageMediator
 
     @Override
     public boolean isScrollViewInitialized() {
-        Stream stream = mCoordinator.getStream();
-        // During startup the view may not be fully initialized, so we check to see if some basic
-        // view properties (height of the RecyclerView) are sane.
-        return stream != null && stream.getView().getHeight() > 0;
+        if (mFeedEnabled) {
+            Stream stream = mCoordinator.getStream();
+            // During startup the view may not be fully initialized, so we check to see if some
+            // basic view properties (height of the RecyclerView) are sane.
+            return stream != null && stream.getView().getHeight() > 0;
+        } else {
+            ScrollView scrollView = mCoordinator.getScrollViewForPolicy();
+            return scrollView != null && scrollView.getHeight() > 0;
+        }
     }
 
     @Override
     public int getVerticalScrollOffset() {
         // This method returns a valid vertical scroll offset only when the first header view in the
-        // Stream is visible. In all other cases, this returns 0.
+        // Stream is visible.
         if (!isScrollViewInitialized()) return 0;
 
-        int firstChildTop = mCoordinator.getStream().getChildTopAt(0);
-        return firstChildTop != Stream.POSITION_NOT_KNOWN ? -firstChildTop : Integer.MIN_VALUE;
+        if (mFeedEnabled) {
+            int firstChildTop = mCoordinator.getStream().getChildTopAt(0);
+            return firstChildTop != Stream.POSITION_NOT_KNOWN ? -firstChildTop : Integer.MIN_VALUE;
+        } else {
+            return mCoordinator.getScrollViewForPolicy().getScrollY();
+        }
     }
 
     @Override
     public boolean isChildVisibleAtPosition(int position) {
-        return isScrollViewInitialized()
-                && mCoordinator.getStream().isChildAtPositionVisible(position);
+        if (mFeedEnabled) {
+            return isScrollViewInitialized()
+                    && mCoordinator.getStream().isChildAtPositionVisible(position);
+        } else {
+            ScrollView scrollView = mCoordinator.getScrollViewForPolicy();
+            Rect rect = new Rect();
+            scrollView.getHitRect(rect);
+            return scrollView.getChildAt(position).getLocalVisibleRect(rect);
+        }
     }
 
     @Override
@@ -189,6 +253,11 @@ class FeedNewTabPageMediator
 
         // Calculating the snap position should be idempotent.
         assert scrollTo == mSnapScrollHelper.calculateSnapPosition(scrollTo);
-        mCoordinator.getStream().smoothScrollBy(0, scrollTo - initialScroll);
+
+        if (mFeedEnabled) {
+            mCoordinator.getStream().smoothScrollBy(0, scrollTo - initialScroll);
+        } else {
+            mCoordinator.getScrollViewForPolicy().smoothScrollBy(0, scrollTo - initialScroll);
+        }
     }
 }

chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPageView.java

@@ -133,7 +133,8 @@ public class NewTabPageView extends FrameLayout {
         mNewTabPageLayout.initialize(manager, tab, tileGroupDelegate, searchProviderHasLogo,
                 searchProviderIsGoogle, mRecyclerView, mContextMenuManager, mUiConfig);
 
-        mSnapScrollHelper = new SnapScrollHelper(mManager, mNewTabPageLayout, mRecyclerView);
+        mSnapScrollHelper = new SnapScrollHelper(mManager, mNewTabPageLayout);
+        mSnapScrollHelper.setView(mRecyclerView);
         mRecyclerView.setSnapScrollHelper(mSnapScrollHelper);
         addView(mRecyclerView);
 

chrome/android/java/src/org/chromium/chrome/browser/ntp/SnapScrollHelper.java

@@ -6,6 +6,7 @@ package org.chromium.chrome.browser.ntp;
 
 import android.annotation.SuppressLint;
 import android.content.res.Resources;
+import android.support.annotation.NonNull;
 import android.view.MotionEvent;
 import android.view.View;
 
@@ -21,11 +22,11 @@ public class SnapScrollHelper {
 
     private final NewTabPageManager mManager;
     private final NewTabPageLayout mNewTabPageLayout;
-    private final View mView;
     private final Runnable mSnapScrollRunnable;
     private final int mToolbarHeight;
     private final int mSearchBoxTransitionLength;
 
+    private View mView;
     private boolean mPendingSnapScroll;
     private int mLastScrollY = -1;
 
@@ -33,20 +34,30 @@ public class SnapScrollHelper {
      * @param manager The {@link NewTabPageManager} to get information about user interactions on
      *                the {@link NewTabPage}.
      * @param newTabPageLayout The {@link NewTabPageLayout} associated with the {@link NewTabPage}.
-     * @param view The view on which this class needs to handle snap scroll.
      */
-    public SnapScrollHelper(NewTabPageView.NewTabPageManager manager,
-            NewTabPageLayout newTabPageLayout, View view) {
+    public SnapScrollHelper(
+            NewTabPageView.NewTabPageManager manager, NewTabPageLayout newTabPageLayout) {
         mManager = manager;
         mNewTabPageLayout = newTabPageLayout;
-        mView = view;
         mSnapScrollRunnable = new SnapScrollRunnable();
 
-        Resources res = view.getResources();
+        Resources res = newTabPageLayout.getResources();
         mToolbarHeight = res.getDimensionPixelSize(R.dimen.toolbar_height_no_shadow)
                 + res.getDimensionPixelSize(R.dimen.toolbar_progress_bar_height);
         mSearchBoxTransitionLength =
                 res.getDimensionPixelSize(R.dimen.ntp_search_box_transition_length);
+    }
+
+    /** @param view The view on which this class needs to handle snap scroll. */
+    public void setView(@NonNull View view) {
+        if (mView != null) {
+            mPendingSnapScroll = false;
+            mLastScrollY = -1;
+            mView.removeCallbacks(mSnapScrollRunnable);
+            mView.setOnTouchListener(null);
+        }
+
+        mView = view;
 
         @SuppressLint("ClickableViewAccessibility")
         View.OnTouchListener onTouchListener = (v, event) -> {

chrome/android/java/src/org/chromium/chrome/browser/preferences/PrefChangeRegistrar.java

@@ -45,6 +45,17 @@ public class PrefChangeRegistrar {
         nativeAdd(mNativeRegistrar, preference);
     }
 
+    /**
+     * Remove an observer for the specified preference if it has previously been added.
+     * @param preference The specified preference.
+     */
+    public void removeObserver(@Pref int preference) {
+        PrefObserver observer = mObservers.get(preference);
+        if (observer == null) return;
+        mObservers.remove(preference);
+        nativeRemove(mNativeRegistrar, preference);
+    }
+
     /**
      * Destroy native PrefChangeRegistrar.
      */
@@ -64,5 +75,6 @@ public class PrefChangeRegistrar {
 
     private native long nativeInit();
     private native void nativeAdd(long nativePrefChangeRegistrarAndroid, int preference);
+    private native void nativeRemove(long nativePrefChangeRegistrarAndroid, int preference);
     private native void nativeDestroy(long nativePrefChangeRegistrarAndroid);
 }

chrome/browser/android/preferences/pref_change_registrar_android.cc

@@ -40,6 +40,13 @@ void PrefChangeRegistrarAndroid::Add(JNIEnv* env,
                  base::Unretained(this), j_pref_index));
 }
 
+void PrefChangeRegistrarAndroid::Remove(JNIEnv* env,
+                                        const JavaParamRef<jobject>& obj,
+                                        const jint j_pref_index) {
+  pref_change_registrar_.Remove(
+      PrefServiceBridge::GetPrefNameExposedToJava(j_pref_index));
+}
+
 void PrefChangeRegistrarAndroid::OnPreferenceChange(const int pref_index) {
   JNIEnv* env = AttachCurrentThread();
   Java_PrefChangeRegistrar_onPreferenceChange(

chrome/browser/android/preferences/pref_change_registrar_android.h

@@ -23,6 +23,9 @@ class PrefChangeRegistrarAndroid {
   void Add(JNIEnv* env,
            const JavaParamRef<jobject>& obj,
            const jint j_pref_index);
+  void Remove(JNIEnv* env,
+              const JavaParamRef<jobject>& obj,
+              const jint j_pref_index);
 
  private:
   ~PrefChangeRegistrarAndroid();