Implement a slide-in pane for bookmarks.

chrome/browser/resources/pdf/index-material.css

 /* 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. */
 
 @font-face {
   font-family: 'Roboto';
   font-style: normal;
   font-weight: 400;
   src: local('Roboto Regular'), local('Roboto-Regular'), url(chrome://resources/roboto/roboto.woff2) format('woff2');
   unicode-range: U+0460-052F, U+20B4, U+2DE0-2DFF, U+A640-A69F;
@@ skipping 38 matching lines @@
   position: fixed;
   top: 64px;
   z-index: 1;
 }
 
 #sizer {
   position: absolute;
   z-index: 0;
 }
 
+bookmarks-pane {
+  z-index: 3;

[raymes, 2015/01/27 09:10:54]

The bookmarks should be behind the toolbar so the shadow the toolbar lies over
the bookmarks pane

[Alexandre Carlton, 2015/01/28 00:22:46]

As discussed, the internal paper-dialog within pdf-pane.html resets its z-index
to 12 on every toggle-in. Currently the only way to force it underneath is to
raise the z-index of #toolbar-shadow to 13 (an ugly hack).

[raymes, 2015/01/28 01:10:20]

What can we do about this? Will you investigate and fix it in a separate CL?

+}
+
 viewer-toolbar {
   visibility: hidden;
   white-space: nowrap;
   z-index: 3;
 }
 
 viewer-page-indicator {
   visibility: hidden;
   z-index: 3;
 }
 
 viewer-error-screen {
   visibility: hidden;
   z-index: 2;
 }
 
 viewer-password-screen {
   visibility: hidden;
   z-index: 2;
 }