Implement a slide-in pane for bookmarks.

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

Index: chrome/browser/resources/pdf/index-material.css
diff --git a/chrome/browser/resources/pdf/index-material.css b/chrome/browser/resources/pdf/index-material.css
index 7f0bf98a6bcab61c9afce5e05ba4cf2b7bd0f2fb..b49d734c1fa8da58886f989542fffcf79b908ab1 100644
--- a/chrome/browser/resources/pdf/index-material.css
+++ b/chrome/browser/resources/pdf/index-material.css
@@ -56,6 +56,10 @@ paper-progress::shadow #progressContainer {
   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;