Move `clearSelection` function to SidebarContentController

This function is no longer inherited from the parent scope since
`<sidebar-content>` is now a component.

Since this helper function is only used by the sidebar, move it
to the SidebarContentController controller.

src/sidebar/app-controller.js

@@ -5,7 +5,6 @@ var scrollIntoView = require('scroll-into-view');
 var events = require('./events');
 var parseAccountID = require('./filter/persona').parseAccountID;
 var scopeTimeout = require('./util/scope-timeout');
-var uiConstants = require('./ui-constants');
 var serviceConfig = require('./service-config');
 var bridgeEvents = require('../shared/bridge-events');
 
@@ -142,16 +141,6 @@ module.exports = function AppController(
     session.logout();
   };
 
-  $scope.clearSelection = function () {
-    var selectedTab = annotationUI.getState().selectedTab;
-    if (!annotationUI.getState().selectedTab || annotationUI.getState().selectedTab === uiConstants.TAB_ORPHANS) {
-      selectedTab = uiConstants.TAB_ANNOTATIONS;
-    }
-
-    annotationUI.clearSelectedAnnotations();
-    annotationUI.selectTab(selectedTab);
-  };
-
   $scope.search = {
     query: function () {
       return annotationUI.getState().filterQuery;

src/sidebar/components/sidebar-content.js

@@ -4,6 +4,7 @@ var SearchClient = require('../search-client');
 var events = require('../events');
 var memoize = require('../util/memoize');
 var tabs = require('../tabs');
+var uiConstants = require('../ui-constants');
 
 function firstKey(object) {
   for (var k in object) {
@@ -324,6 +325,16 @@ function SidebarContentController(
   this.topLevelThreadCount = function () {
     return thread().totalChildren;
   };
+
+  this.clearSelection = function () {
+    var selectedTab = annotationUI.getState().selectedTab;
+    if (!annotationUI.getState().selectedTab || annotationUI.getState().selectedTab === uiConstants.TAB_ORPHANS) {
+      selectedTab = uiConstants.TAB_ANNOTATIONS;
+    }
+
+    annotationUI.clearSelectedAnnotations();
+    annotationUI.selectTab(selectedTab);
+  };
 }
 
 module.exports = {