[ios] Install ManagedBookmarksPolicyHandler

This CL installs the ManagedBookmarksPolicyHandler
in policy handler list factory. This is guarded by
a command-line switch: '--install-managed-bookmarks-handler'

Bug: 1065187
Change-Id: Ie103fd92185b1397a3e5da30afd1da9b8384dd1a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2142774
Commit-Queue: edchin <edchin@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#757934}

ios/chrome/browser/policy/BUILD.gn

@@ -20,6 +20,7 @@ source_set("policy") {
 
   deps = [
     "//base",
+    "//components/bookmarks/managed",
     "//components/password_manager/core/common",
     "//components/policy:generated",
     "//components/policy/core/common",

ios/chrome/browser/policy/configuration_policy_handler_list_factory.mm

@@ -6,6 +6,7 @@
 
 #include "base/bind.h"
 #include "base/logging.h"
+#include "components/bookmarks/managed/managed_bookmarks_policy_handler.h"
 #include "components/password_manager/core/common/password_manager_pref_names.h"
 #include "components/policy/core/browser/configuration_policy_handler.h"
 #include "components/policy/core/browser/configuration_policy_handler_list.h"
@@ -51,6 +52,12 @@ std::unique_ptr<policy::ConfigurationPolicyHandlerList> BuildPolicyHandlerList(
           kSimplePolicyMap[i].policy_name, kSimplePolicyMap[i].preference_path,
           kSimplePolicyMap[i].value_type));
     }
+
+    if (ShouldInstallManagedBookmarksPolicyHandler()) {
+      handlers->AddHandler(
+          std::make_unique<bookmarks::ManagedBookmarksPolicyHandler>(
+              chrome_schema));
+    }
   }
 
   return handlers;