[MD settings] settings icon color per spec

This CL changes the default icon color to the value
specified by Alan (UX designer).

BUG=425627

Review URL: https://codereview.chromium.org/1603913003

Cr-Commit-Position: refs/heads/master@{#371108}
diff --git a/chrome/browser/resources/settings/settings_shared.css b/chrome/browser/resources/settings/settings_shared.css
index ba6bb13..90d956d8 100644
--- a/chrome/browser/resources/settings/settings_shared.css
+++ b/chrome/browser/resources/settings/settings_shared.css
@@ -7,6 +7,19 @@
  * Common styles for Material Design settings.
  */
 
+h2 {
+  color: #9e9e9e;
+  font-size: 100%;
+  font-weight: normal;
+  margin-bottom: 20px;
+  margin-top: 30px;
+}
+
+
+iron-icon {
+  color: #969696;
+}
+
 paper-button {
   margin: 0;
   min-width: auto;
@@ -22,14 +35,6 @@
   white-space: nowrap;
 }
 
-h2 {
-  color: #9e9e9e;
-  font-size: 100%;
-  font-weight: normal;
-  margin-bottom: 20px;
-  margin-top: 30px;
-}
-
 .button-row {
   display: flex;
   margin-top: 25px;