Add crOS Account Manager settings subpage search control

Conditionally enabled only when Account Manager feature flag is set.

Bug: 876280, 833797
Change-Id: I4ecdfae67f01ca1dbf227b912d976e901b8fa2b3
Reviewed-on: https://chromium-review.googlesource.com/1199362Reviewed-by: Scott Chen <scottchen@chromium.org>
Commit-Queue: Kush Sinha <sinhak@chromium.org>
Cr-Commit-Position: refs/heads/master@{#588076}

chrome/browser/resources/settings/people_page/people_page.html

@@ -440,13 +440,14 @@
           <settings-change-picture></settings-change-picture>
         </settings-subpage>
       </template>
-      <template is="dom-if" route-path="/accountManager">
-        <!-- TODO(sinhak): remove no-search and add associated-control once
-            one becomes available. -->
-        <settings-subpage no-search
-          page-title="$i18n{accountManagerPageTitle}">
-          <settings-account-manager></settings-account-manager>
-        </settings-subpage>
+      <template is="dom-if" if="[[isAccountManagerEnabled_]]">
+        <template is="dom-if" route-path="/accountManager">
+          <settings-subpage
+              associated-control="[[$$('#account-manager-subpage-trigger')]]"
+              page-title="$i18n{accountManagerPageTitle}">
+            <settings-account-manager></settings-account-manager>
+          </settings-subpage>
+        </template>
       </template>
 </if>
 <if expr="not chromeos">