Update some webui question mark icons to SVG.

chrome/browser/resources/about_memory.css

 /* Copyright (c) 2012 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file. */
 
 body {
   font-size: 84%;
   margin: 0;
   min-width: 45em;
   padding: 0.75em;
 }
@@ skipping 32 matching lines @@
 }
 
 div#header {
   background: rgb(82, 150, 222);
   background-size: 100%;
   border: 1px solid rgb(58, 117, 189);
   border-radius: 6px;
   color: white;
   margin-bottom: 0.75em;
   overflow: hidden;
-  padding: 0.6em 1em 0.75em 0;
+  padding: 0.5em 0;
   position: relative;
   text-shadow: 0 0 2px black;
 }
 
 div#header h1 {
-  background: url(chrome://resources/images/gear.png) 12px 60% no-repeat;
   color: white;
   display: inline;
-  margin: 0;
-  padding-left: 37px;
+}
+
+div#header h1::before {
+  /* grit doesn't flatten -webkit-mask, so define the properties separately
+   * for now. */
+  -webkit-mask-image: url(../../../ui/webui/resources/images/settings.svg);
+  -webkit-mask-position: center;
+  -webkit-mask-repeat: no-repeat;
+  -webkit-mask-size: 24px;
+  background-color: white;
+  content: '';
+  display: inline-block;
+  height: 20px;
+  vertical-align: middle;
+  width: 37px;
 }
 
 div#header p {
   color: white;
   display: inline;
   font-size: 84%;
   font-style: italic;
   margin: 0;
   padding: 0;
   padding-left: 0.4em;
@@ skipping 177 matching lines @@
   text-align: center;
 }
 
 table.list#browserComparison .name {
   background-position: 5px center;
   background-repeat: no-repeat;
   padding-left: 25px;
 }
 
 div.help {
-  background: url(chrome://resources/images/help.png) center bottom no-repeat;
+  -webkit-mask-box-image: url(../../../ui/webui/resources/images/help.svg);
+  background-color: rgb(66, 133, 244);
   display: inline-block;
-  height: 14px;
-  margin: -1px 0;
+  height: 16px;
+  margin: -1px 0 0 0;
   opacity: 0.33;
-  width: 14px;
+  vertical-align: bottom;
+  width: 16px;
 }
 
 div.help:hover {
   opacity: 1;
 }
 
 div.help div {
   display: none;
 }
 
@@ skipping 12 matching lines @@
 
 #helpTooltip p {
   margin: 0.6em 0;
 }
 
 div.otherbrowsers {
   font-size: 84%;
   text-align: center;
   width: 100%;
 }