When possible, draw the toolbar shadow with the compositor

chrome/android/java/src/org/chromium/chrome/browser/fullscreen/ChromeFullscreenManager.java

 // Copyright 2014 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.fullscreen;
 
 import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
 import android.animation.ObjectAnimator;
 import android.app.Activity;
@@ skipping 524 matching lines @@
      * @param hide Whether or not to force the top controls Android view to hide.  If this is
      *             {@code false} the top controls Android view will show/hide based on position, if
      *             it is {@code true} the top controls Android view will always be hidden.
      */
     public void setHideTopControlsAndroidView(boolean hide) {
         if (mTopControlsAndroidViewHidden == hide) return;
         mTopControlsAndroidViewHidden = hide;
         scheduleVisibilityUpdate();
     }
 
+    /**
+     * @return True if the Android version of the top controls are hidden. This includes cases
+     *         where the controls offset is < 0;
+     */
+    public boolean isTopControlsAndroidViewHidden() {
+        return mTopControlsAndroidViewHidden || getControlOffset() < 0;
+    }
+
     private boolean shouldShowAndroidControls() {
         if (mTopControlsAndroidViewHidden) return false;
 
         boolean showControls = getControlOffset() == 0;
         ContentViewCore contentViewCore = getActiveContentViewCore();
         if (contentViewCore == null) return showControls;
         ViewGroup contentView = contentViewCore.getContainerView();
 
         for (int i = 0; i < contentView.getChildCount(); i++) {
             View child = contentView.getChildAt(i);
@@ skipping 180 matching lines @@
         mControlAnimation.start();
         mCurrentAnimationIsShowing = show;
     }
 
     @Override
     public void onContentViewScrollingStateChanged(boolean scrolling) {
         mContentViewScrolling = scrolling;
         if (!scrolling) updateVisuals();
     }
 }