Tag some of Mojo heap allocations for the heap profiler.

ios/web/webui/mojo_facade.mm

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/web/webui/mojo_facade.h"
 
+#include <utility>
+
 #import <Foundation/Foundation.h>
 
 #import "base/ios/block_types.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #import "base/mac/bind_objc_block.h"
+#include "base/memory/ptr_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/values.h"
 #import "ios/web/public/web_state/js/crw_js_injection_evaluator.h"
 #include "ios/web/public/web_thread.h"
 #include "mojo/public/cpp/system/core.h"
 #include "services/service_manager/public/interfaces/interface_provider.mojom.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
@@ skipping 226 matching lines @@
   int callback_id;
   CHECK(args->GetInteger("callbackId", &callback_id));
 
   mojo::Watcher::ReadyCallback callback = base::BindBlockArc(^(
       MojoResult result) {
     NSString* script =
         [NSString stringWithFormat:@"__crWeb.mojo.signalWatch(%d, %d)",
                                    callback_id, result];
     [script_evaluator_ executeJavaScript:script completionHandler:nil];
   });
-
-  mojo::Watcher& watcher = watchers_[++last_watch_id_];
-  watcher.Start(static_cast<mojo::Handle>(handle), signals, callback);
+  mojo::Watcher* watcher = new mojo::Watcher(FROM_HERE);
+  watchers_.insert(std::make_pair(++last_watch_id_, base::WrapUnique(watcher)));
+  watcher->Start(static_cast<mojo::Handle>(handle), signals, callback);
   return ValueFromInteger(last_watch_id_);
 }
 
 std::unique_ptr<base::Value> MojoFacade::HandleSupportCancelWatch(
     const base::DictionaryValue* args) {
   int watch_id = 0;
   CHECK(args->GetInteger("watchId", &watch_id));
   watchers_.erase(watch_id);
   return nullptr;
 }
 
 }  // namespace web