Add new NTP layout with snippet cards and hide it behind a flag

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

-// Copyright 2015 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.ntp;
-
-import android.content.Context;
-import android.graphics.Canvas;
-import android.os.Build;
-import android.util.AttributeSet;
-import android.util.Log;
-import android.view.GestureDetector;
-import android.view.KeyEvent;
-import android.view.MotionEvent;
-import android.view.View;
-import android.view.inputmethod.EditorInfo;
-import android.view.inputmethod.InputConnection;
-import android.widget.ScrollView;
-
-import org.chromium.chrome.R;
-import org.chromium.chrome.browser.widget.FadingShadow;
-
-/**
- * Simple wrapper on top of a ScrollView that will acquire focus when tapped.  Ensures the
- * New Tab page receives focus when clicked.
- */
-public class NewTabScrollView extends ScrollView {
-
-    private static final String TAG = "NewTabScrollView";
-
-    /**
-     * Listener for scroll changes.
-     */
-    public interface OnScrollListener {
-        /**
-         * Triggered when the scroll changes.  See ScrollView#onScrollChanged for more
-         * details.
-         */
-        void onScrollChanged(int l, int t, int oldl, int oldt);
-    }
-
-    private GestureDetector mGestureDetector;
-    private OnScrollListener mOnScrollListener;
-
-    private NewTabPageLayout mNewTabPageLayout;
-
-    private FadingShadow mFadingShadow;
-
-    /**
-     * Constructor needed to inflate from XML.
-     */
-    public NewTabScrollView(Context context, AttributeSet attrs) {
-        super(context, attrs);
-
-        mGestureDetector = new GestureDetector(
-                getContext(), new GestureDetector.SimpleOnGestureListener() {
-                    @Override
-                    public boolean onSingleTapUp(MotionEvent e) {
-                        boolean retVal = super.onSingleTapUp(e);
-                        requestFocus();
-                        return retVal;
-                    }
-                });
-    }
-
-    /**
-     * Enables drawing a shadow at the bottom of the view when the view's content extends beyond
-     * the bottom of the view. This is exactly the same as a fading edge, except that the shadow
-     * color can have an alpha component, whereas a fading edge color must be opaque.
-     *
-     * @param shadowColor The color of the shadow, e.g. 0x11000000.
-     */
-    public void enableBottomShadow(int shadowColor) {
-        mFadingShadow = new FadingShadow(shadowColor);
-        setFadingEdgeLength(getResources().getDimensionPixelSize(R.dimen.ntp_shadow_height));
-    }
-
-    @Override
-    protected void onFinishInflate() {
-        super.onFinishInflate();
-
-        View child = getChildAt(0);
-        if (child instanceof NewTabPageLayout) mNewTabPageLayout = (NewTabPageLayout) child;
-    }
-
-    @Override
-    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
-        if (mNewTabPageLayout != null) {
-            mNewTabPageLayout.setParentScrollViewportHeight(
-                    MeasureSpec.getSize(heightMeasureSpec));
-        }
-        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
-    }
-
-    @Override
-    public boolean onInterceptTouchEvent(MotionEvent ev) {
-        mGestureDetector.onTouchEvent(ev);
-        return super.onInterceptTouchEvent(ev);
-    }
-
-    @Override
-    public boolean onTouchEvent(MotionEvent ev) {
-        // Action down would already have been handled in onInterceptTouchEvent
-        if (ev.getActionMasked() != MotionEvent.ACTION_DOWN) {
-            mGestureDetector.onTouchEvent(ev);
-        }
-        try {
-            return super.onTouchEvent(ev);
-        } catch (IllegalArgumentException ex) {
-            // In JB MR0 and earlier, an ACTION_MOVE that is not preceded by an ACTION_DOWN event
-            // causes a crash. This can happen under normal circumstances (e.g. going back to the
-            // NTP while a finger is down on the screen) and should not crash. The most reliable way
-            // to prevent this crash is to catch the exception. http://crbug.com/293822
-            if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR1
-                    && ev.getActionMasked() == MotionEvent.ACTION_MOVE
-                    && "pointerIndex out of range".equals(ex.getMessage())) {
-                Log.d(TAG, "Ignoring pointerIndex out of range exception.");
-                return true;
-            }
-            throw ex;
-        }
-    }
-
-    /**
-     * Sets the listener to be notified of scroll changes.
-     * @param listener The listener to be updated on scroll changes.
-     */
-    public void setOnScrollListener(OnScrollListener listener) {
-        mOnScrollListener = listener;
-    }
-
-    @Override
-    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
-        super.onScrollChanged(l, t, oldl, oldt);
-        if (mOnScrollListener != null) mOnScrollListener.onScrollChanged(l, t, oldl, oldt);
-    }
-
-    @Override
-    public void focusableViewAvailable(View v) {
-        // To avoid odd jumps during NTP animation transitions, we do not attempt to give focus
-        // to child views if this scroll view already has focus.
-        if (hasFocus()) return;
-        super.focusableViewAvailable(v);
-    }
-
-    @Override
-    public boolean executeKeyEvent(KeyEvent event) {
-        // Ignore all key events except arrow keys and spacebar. Otherwise, the ScrollView consumes
-        // unwanted events (including the hardware menu button and app-level keyboard shortcuts).
-        // http://crbug.com/308322
-        switch (event.getKeyCode()) {
-            case KeyEvent.KEYCODE_DPAD_UP:
-            case KeyEvent.KEYCODE_DPAD_DOWN:
-            case KeyEvent.KEYCODE_SPACE:
-                return super.executeKeyEvent(event);
-            default:
-                return false;
-        }
-    }
-
-    @Override
-    public InputConnection onCreateInputConnection(EditorInfo outAttrs) {
-        // Fixes lanscape transitions when unfocusing the URL bar: crbug.com/288546
-        outAttrs.imeOptions = EditorInfo.IME_FLAG_NO_FULLSCREEN;
-        return super.onCreateInputConnection(outAttrs);
-    }
-
-    @Override
-    protected void dispatchDraw(Canvas canvas) {
-        super.dispatchDraw(canvas);
-        if (mFadingShadow != null) {
-            setVerticalFadingEdgeEnabled(true);
-            float shadowStrength = getBottomFadingEdgeStrength();
-            float shadowHeight = getVerticalFadingEdgeLength();
-            setVerticalFadingEdgeEnabled(false);
-            mFadingShadow.drawShadow(this, canvas, FadingShadow.POSITION_BOTTOM,
-                    shadowHeight, shadowStrength);
-        }
-    }
-}