Fix ChromeSwitchCompat thumb drawable and tint color

chrome/android/java/src/org/chromium/chrome/browser/widget/ChromeSwitchCompat.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.content.res.ColorStateList;
+import android.graphics.PorterDuff;
+import android.graphics.drawable.Drawable;
 import android.support.v7.widget.SwitchCompat;
 import android.util.AttributeSet;
 import android.view.accessibility.AccessibilityEvent;
 import android.view.accessibility.AccessibilityNodeInfo;
 import android.widget.Switch;
 
+import org.chromium.chrome.R;
+
 /**
  * This class fixes the accessibility of SwitchCompat so it's read as "on switch" instead of
  * "checkbox checked". http://crbug.com/441702
  *
  * TalkBack doesn't recognize the SwitchCompat class, so it reads events with that classname as
  * "Checkbox". This works around the bug by marking accessibility events from SwitchCompat with the
  * Switch class name, which TalkBack recognizes.
  *
+ * It also fixes the thumb drawable being too small and disappearing on certain devices
+ * and the disabled tint color being incorrect. http://crbug.com/455327
+ *
  * TODO(newt): Delete this class once the support library is fixed. http://b/19110477
  */
 public class ChromeSwitchCompat extends SwitchCompat {
+    private Drawable mThumbDrawable;
+    private ColorStateList mTint;
 
     /**
      * Constructor for inflating from XML.
      */
     public ChromeSwitchCompat(Context context, AttributeSet attrs) {
         super(context, attrs);
+        super.setThumbResource(R.drawable.switch_thumb);

[newt (away), 2015/02/09 21:38:05]

don't need "super."

[Theresa, 2015/02/09 23:01:15]

Done.

+        mThumbDrawable = getThumbDrawable();

[newt (away), 2015/02/09 21:38:05]

Call mutate() on mThumbDrawable since you're changing its color filter below.

[Theresa, 2015/02/09 23:01:15]

Done.

+        mTint = getResources().getColorStateList(R.color.switch_thumb_tint);
     }
 
     @Override
     public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
         super.onInitializeAccessibilityEvent(event);
         event.setClassName(Switch.class.getName());
     }
 
     @Override
     public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
         super.onInitializeAccessibilityNodeInfo(info);
         info.setClassName(Switch.class.getName());
     }
+
+    @Override
+    protected void drawableStateChanged() {
+        super.drawableStateChanged();
+        updateThumbTintColor();
+    }
+
+    private boolean updateThumbTintColor() {
+        if (mTint == null) return false;
+        mThumbDrawable.setColorFilter(mTint.getColorForState(mThumbDrawable.getState(), 0),
+                PorterDuff.Mode.SRC_IN);
+        return true;
+    }
 }