Remove all remaining HashMap and HashSet usages except dart_string_cache

sky/engine/tonic/dart_timer_heap.cc

 // Copyright 2015 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.
 
 #include "sky/engine/tonic/dart_timer_heap.h"
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
 #include "base/time/time.h"
 #include "sky/engine/tonic/dart_api_scope.h"
 #include "sky/engine/tonic/dart_invoke.h"
 #include "sky/engine/tonic/dart_isolate_scope.h"
 #include "sky/engine/tonic/dart_state.h"
 
 namespace blink {
 
 DartTimerHeap::DartTimerHeap() : next_timer_id_(1), weak_factory_(this) {
 }
 
 DartTimerHeap::~DartTimerHeap() {
 }
 
 int DartTimerHeap::Add(PassOwnPtr<Task> task) {
   int id = next_timer_id_++;
   Schedule(id, task);
   return id;
 }
 
 void DartTimerHeap::Remove(int id) {
-  heap_.remove(id);
+  heap_.erase(id);
 }
 
 void DartTimerHeap::Schedule(int id, PassOwnPtr<Task> task) {
   base::TimeDelta delay = task->delay;
-  heap_.add(id, task);
+  heap_[id] = task;
   base::MessageLoop::current()->PostDelayedTask(FROM_HERE,
     base::Bind(&DartTimerHeap::Run, weak_factory_.GetWeakPtr(), id), delay);
 }
 
 void DartTimerHeap::Run(int id) {
   auto it = heap_.find(id);
   if (it == heap_.end())
     return;
-  OwnPtr<Task> task = it->value.release();
-  heap_.remove(it);
+  OwnPtr<Task> task = it->second.release();
+  heap_.erase(it);
   if (!task->closure.dart_state())
     return;
   DartIsolateScope scope(task->closure.dart_state()->isolate());
   DartApiScope api_scope;
   DartInvokeAppClosure(task->closure.value(), 0, nullptr);
   if (task->repeating)
     Schedule(id, task.release());
 }
 
 }