Peek new infobars behind existing ones

chrome/android/java/res/layout/main.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!-- 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. -->
 
 <merge xmlns:android="http://schemas.android.com/apk/res/android">
     <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:orientation="vertical">
 
         <android.support.design.widget.CoordinatorLayout
             android:id="@+id/coordinator"
             android:layout_width="match_parent"
             android:layout_height="0dp"
             android:layout_weight="1" >
 
             <org.chromium.chrome.browser.compositor.CompositorViewHolder
                 android:id="@+id/compositor_view_holder"
                 android:layout_width="match_parent"
                 android:layout_height="match_parent" />
 
             <org.chromium.chrome.browser.snackbar.BottomContainer
                 android:id="@+id/bottom_container"
                 android:layout_width="match_parent"
                 android:layout_height="match_parent"
-                android:layout_gravity="start|bottom" />
+                android:layout_gravity="start|bottom"
+                android:clipChildren="false" />

[Ted C, 2017/05/17 17:55:54]

I think we should conditionally set this.  I have a strong suspicion that
Android would have to disable some optimizations with this enabled.

[mdjones, 2017/05/17 21:05:19]

I changed this to be set based on whether the infobar container is running an
animation. I chose to get the container class by id rather than plumbing it
down; I can go this route if you prefer.

 
             <ViewStub
                 android:id="@+id/bottombar_stub"
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"
                 android:layout_marginTop="-4dp"
                 android:layout_gravity="start|bottom"
                 android:inflatedId="@+id/bottombar"
                 android:layout="@layout/custom_tabs_bottombar" />
 
@@ skipping 61 matching lines @@
     </LinearLayout>
 
     <!-- This empty view is used as the anchor for custom menu -->
     <View
         android:id="@+id/menu_anchor_stub"
         android:layout_width="0px"
         android:layout_height="0px"
         android:layout_gravity="bottom|start"
         />
 </merge>