Fix experimental app list contents switcher being positioned incorrectly on profile switch.

This CL fixes an issue with the experimental app launcher's buttons being laid
out above the app grid due to the contents view being re-added on profile
switch. This has been fixed by ensuring the contents view is always added to
the same position.

BUG=371695

Review URL: https://codereview.chromium.org/272923002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@269550 0039d316-1c4b-4281-b951-d872f2087c98

ui/app_list/views/app_list_main_view.cc

@@ -38,6 +38,8 @@ const int kInnerPadding = 1;
 // The maximum allowed time to wait for icon loading in milliseconds.
 const int kMaxIconLoadingWaitTimeInMs = 50;
 
+const int kContentsViewIndex = 1;
+
 }  // namespace
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -107,7 +109,7 @@ AppListMainView::AppListMainView(AppListViewDelegate* delegate,
 void AppListMainView::AddContentsView() {
   contents_view_ = new ContentsView(
       this, pagination_model_, model_, delegate_);
-  AddChildView(contents_view_);
+  AddChildViewAt(contents_view_, kContentsViewIndex);
 
   search_box_view_->set_contents_view(contents_view_);