MD Settings: make input label and error font size relative.

chrome/browser/resources/settings/settings_vars_css.html

 <link rel="import" href="chrome://resources/cr_elements/shared_vars_css.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-styles/color.html">
 
 <!-- Common css variables for Material Design settings. -->
 <style is="custom-style">
   /* We keep our vars in sort order, though some vars must be defined prior to
    * others. The --settings-* vars are defined explicitly prior to the --paper-*
    * and --iron-* vars.
    */
   :root {
@@ skipping 85 matching lines @@
        * 40px"), since paper-icon-button>iron-icon width and height are
        * hardcoded to 100%.
        */
       padding: 10px;
     };
     --paper-input-container-focus-color: var(--google-blue-500);
     --paper-input-container-input: {
       color: inherit;
       font-size: inherit;
       font-weight: inherit;
+      line-height: inherit;
       vertical-align: baseline;
     };
+    --paper-input-container-label: {
+      font-size: inherit;
+      line-height: inherit;
+    }
+    --paper-input-error: {
+      font-size: 92.31%; /* Should be 12px when 100% is 13px. */
+      line-height: inherit;
+      overflow: visible; /* Half-visible error message is not useful at all. */
+    }
     --paper-input-max-width: 264px;
     --paper-radio-button-ink-size: 40px;
     --paper-radio-button-label-color: inherit;
     --paper-radio-button-size: 16px;
     --paper-radio-group-item-padding: 0;
 
     --paper-toggle-button-checked-bar: var(--settings-toggle-bar-size);
     --paper-toggle-button-checked-bar-color: var(--settings-toggle-color);
     --paper-toggle-button-checked-button: {
       @apply(--settings-toggle-button-size);
       transform: translate(18px, 0);
     };
     --paper-toggle-button-checked-button-color: var(--settings-toggle-color);
     --paper-toggle-button-label-spacing: 0;
     --paper-toggle-button-unchecked-bar: var(--settings-toggle-bar-size);
     --paper-toggle-button-unchecked-button: var(--settings-toggle-button-size);
     --paper-toggle-button-unchecked-ink: var(--settings-toggle-ink-size);
 
     --settings-input-underline: {
       border-color: var(--paper-grey-300);
     }
 
     --paper-input-container-underline: var(--settings-input-underline);
   }
 </style>