[Android]Fix a regression that snackbar sits behind the scrim

chrome/android/java/src/org/chromium/chrome/browser/compositor/CompositorViewHolderBehavior.java

Index: chrome/android/java/src/org/chromium/chrome/browser/compositor/CompositorViewHolderBehavior.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/compositor/CompositorViewHolderBehavior.java b/chrome/android/java/src/org/chromium/chrome/browser/compositor/CompositorViewHolderBehavior.java
new file mode 100644
index 0000000000000000000000000000000000000000..4828d19ecdb44f302ea901eab9be8872006a077f
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/compositor/CompositorViewHolderBehavior.java
@@ -0,0 +1,56 @@
+// 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.compositor;
+
+import android.content.Context;
+import android.support.design.widget.CoordinatorLayout;
+import android.support.design.widget.CoordinatorLayout.Behavior;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import android.view.View;
+
+/**
+ * Default {@link Behavior} for widgets that are children of {@link CompositorViewHolder} and want
+ * to handle touch events.
+ */
+public class CompositorViewHolderBehavior extends Behavior<View> {
+    private boolean mShouldIntercept;
+
+    /**
+     * Constructs the object programmatically.
+     */
+    public CompositorViewHolderBehavior() {
+        super();
+    }
+
+    /**
+     * Constructs the object during inflation.
+     */
+    public CompositorViewHolderBehavior(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    @Override
+    public boolean onInterceptTouchEvent(CoordinatorLayout parent, View child, MotionEvent ev) {
+        mShouldIntercept = child.getVisibility() == View.VISIBLE && isTouchInBound(ev, child);
+        return mShouldIntercept;
+    }
+
+    @Override
+    public boolean onTouchEvent(CoordinatorLayout parent, View child, MotionEvent ev) {
+        if (!mShouldIntercept) return false;
+        ev.offsetLocation(-child.getX(), -child.getY());
+        child.dispatchTouchEvent(ev);
+        return true;
+    }
+
+    /**
+     * @return Whether the {@link MotionEvent} happens within the bound of the given {@link View}.
+     */
+    private static boolean isTouchInBound(MotionEvent ev, View view) {
+        return ev.getX() >= view.getX() && ev.getX() - view.getX() <= view.getWidth()
+                && ev.getY() >= view.getY() && ev.getY() - view.getY() <= view.getHeight();
+    }
+}