PDF Viewer Update: Make toolbar reactive to narrow screens

Disallow wrapping within the #end div and add a 20px padding to the
left.

When window width is less than or equal to 600px, do not display the
PDF title and the zoom input.

Bug: 1108453
Change-Id: I60dbd2ada5a6a81cdf9f40daf6019889498d308f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2314788
Commit-Queue: Daniel Hosseinian <dhoss@chromium.org>
Reviewed-by: John Lee <johntlee@chromium.org>
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791521}

chrome/browser/resources/pdf/elements/viewer-pdf-toolbar-new.html

@@ -42,7 +42,9 @@
   }
 
   #end {
+    padding-inline-start: 20px;
     text-align: end;
+    white-space: nowrap;
   }
 
   #zoom-controls {
@@ -53,6 +55,13 @@
     padding: 0 6px;
   }
 
+  @media(max-width: 600px) {
+    #title,
+    #zoom-controls input {
+      display: none;
+    }
+  }
+
   viewer-page-selector {
     display: inline-flex;
   }