Fix unbalanced md-select is not centered

md-select is not aligned with its label due to unbalanced paddings 
and a 3px md-select-underline. This Cl fixes this by balancing 
md-select with an additional margin-top and reducing the height of 
md-select-underline to 0px + 1px border.

Bug: 740887
Change-Id: I1b8a5b6bea9c30a686427fdffb96ee05df686259
Reviewed-on: https://chromium-review.googlesource.com/566826
Commit-Queue: Christian Dullweber <dullweber@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487040}

chrome/browser/resources/settings/clear_browsing_data_dialog/clear_browsing_data_dialog.html

@@ -87,6 +87,10 @@
 
       #clearFrom {
         -webkit-margin-start: 0.5em;
+        /* Adjust for 1px md-select-underline and 1px additional bottom padding
+         * to keep md-select's text (without the underline) aligned with
+         * neighboring text that does not have an underline. */
+        margin-top: 2px;
       }
 
       .title .secondary {

ui/webui/resources/html/md_select_css.html

@@ -58,6 +58,7 @@
         -webkit-margin-start: var(--md-select-side-padding);
         border-top: 1px solid var(--paper-grey-300);
         display: block;
+        height: 0;
         margin-bottom: 0;
         margin-top: 0;
       }