[Custom Tabs] Implement Bottombar

chrome/android/java/src/org/chromium/chrome/browser/widget/FadingShadowView.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.widget;
 
 import android.content.Context;
 import android.graphics.Canvas;
 import android.util.AttributeSet;
 import android.view.View;
 
 /**
  * A class that encapsulates {@link FadingShadow} as a self-contained view.
  */
 public class FadingShadowView extends View {
     private FadingShadow mFadingShadow;
     private int mPosition;
-    private float mStrength;
+    private float mStrength = 1f;
 
     /**
      * Constructor for inflating from XML.
      */
     public FadingShadowView(Context context, AttributeSet attrs) {
         super(context, attrs);
     }
 
     /**
      * Sets shadow color and position, please refer to the below function. Note that this function
@@ skipping 26 matching lines @@
     }
 
     @Override
     protected void onDraw(Canvas canvas) {
         super.onDraw(canvas);
         if (mFadingShadow != null) {
             mFadingShadow.drawShadow(this, canvas, mPosition, getHeight(), mStrength);
         }
     }
 }