[MD settings] drawer menu icon into title bar; icon colors

chrome/browser/resources/settings/settings_shared_css.html

 <!-- Common styles for Material Design settings. -->
 <dom-module id="settings-shared">
   <template>
     <style>
       :root {
         --checkbox-margin-start: 2px;
         --checkbox-size: 16px;
         --checkbox-spacing: 18px;
         --iron-icon-fill-color: var(--paper-grey-600);
         --iron-icon-height: 20px;
         --iron-icon-width: 20px;
         --paper-icon-button: {
           width: 36px;
           height: 36px;
         };
         --paper-input-max-width: 264px;
         --settings-background-color: var(--paper-blue-grey-50);
         --settings-secondary: {
           color: var(--paper-grey-600);
           font-weight: 400;
         };
         --settings-error-color: var(--paper-red-700);
         --settings-hover-color: var(--google-grey-300);
 
         /* Some colors use non-MD colors.  These custom colors are specified by
          * UX design (bettes@). */
         --settings-nav-grey: rgb(90, 90, 90);
         --settings-title-bar-background-color: rgb(52, 73, 94);
         --settings-title-bar-color: rgb(255, 255, 255);
+        --settings-title-search-color: rgb(192, 199, 205);
       }
 
       h2 {
         @apply(--layout-center);
         color: var(--paper-grey-500);
         display: flex;
         font-size: 100%;
         font-weight: 500;
         margin: 0;
         min-height: 40px;
@@ skipping 209 matching lines @@
 
       .settings-checkbox-spacer {
         -webkit-margin-start: calc(
             var(--checkbox-margin-start) +
             var(--checkbox-size) +
             var(--checkbox-spacing));
       }
     </style>
   </template>
 </dom-module>