Undo mistaken revert.

content/renderer/media/video_capture_impl_manager.cc

+// Copyright (c) 2011 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 "content/renderer/media/video_capture_impl_manager.h"
+
+#include "base/memory/singleton.h"
+#include "content/common/child_process.h"
+#include "content/common/child_thread.h"
+#include "content/common/video_capture_messages.h"
+#include "content/common/view_messages.h"
+#include "media/base/message_loop_factory_impl.h"
+
+namespace {
+
+// VideoCaptureMessageFilterCreator is to be used as a singleton so we can get
+// access to a shared VideoCaptureMessageFilter.
+// Example usage:
+//   VideoCaptureMessageFilter* filter =
+//       VideoCaptureMessageFilterCreator::SharedFilter();
+
+class VideoCaptureMessageFilterCreator {
+ public:
+  VideoCaptureMessageFilterCreator() {
+    int routing_id;
+    ChildThread::current()->Send(
+        new ViewHostMsg_GenerateRoutingID(&routing_id));
+    filter_ = new VideoCaptureMessageFilter(routing_id);
+    filter_->AddFilter();
+  }
+
+  static VideoCaptureMessageFilter* SharedFilter() {
+    return GetInstance()->filter_.get();
+  }
+
+  static VideoCaptureMessageFilterCreator* GetInstance() {
+    return Singleton<VideoCaptureMessageFilterCreator>::get();
+  }
+
+ private:
+  scoped_refptr<VideoCaptureMessageFilter> filter_;
+};
+
+}  // namespace
+
+VideoCaptureImplManager::VideoCaptureImplManager() {
+  ml_factory_.reset(new media::MessageLoopFactoryImpl());
+  ml_proxy_ = ml_factory_->GetMessageLoopProxy("VC manager");
+}
+
+VideoCaptureImplManager::~VideoCaptureImplManager() {}
+
+// static
+media::VideoCapture* VideoCaptureImplManager::AddDevice(
+    media::VideoCaptureSessionId id,
+    media::VideoCapture::EventHandler* handler) {
+  DCHECK(handler);
+  VideoCaptureImplManager* manager = GetInstance();
+
+  base::AutoLock auto_lock(manager->lock_);
+  Devices::iterator it = manager->devices_.find(id);
+  if (it == manager->devices_.end()) {
+    VideoCaptureImpl* vc =
+        new VideoCaptureImpl(id, manager->ml_proxy_,
+                             VideoCaptureMessageFilterCreator::SharedFilter());
+    manager->devices_[id] = Device(vc, handler);
+    vc->Init();
+    return vc;
+  }
+
+  manager->devices_[id].clients.push_front(handler);
+  return it->second.vc;
+}
+
+// static
+void VideoCaptureImplManager::RemoveDevice(
+    media::VideoCaptureSessionId id,
+    media::VideoCapture::EventHandler* handler) {
+  DCHECK(handler);
+  VideoCaptureImplManager* manager = GetInstance();
+
+  base::AutoLock auto_lock(manager->lock_);
+  Devices::iterator it = manager->devices_.find(id);
+  if (it == manager->devices_.end())
+    return;
+
+  size_t size = it->second.clients.size();
+  it->second.clients.remove(handler);
+
+  if (size == it->second.clients.size() || size > 1)
+    return;
+
+  manager->devices_[id].vc->DeInit(NewRunnableMethod(manager,
+      &VideoCaptureImplManager::FreeDevice, manager->devices_[id].vc));
+  manager->devices_.erase(id);
+  return;
+}
+
+// static
+VideoCaptureImplManager* VideoCaptureImplManager::GetInstance() {
+  return Singleton<VideoCaptureImplManager>::get();
+}
+
+void VideoCaptureImplManager::FreeDevice(VideoCaptureImpl* vc) {
+  delete vc;
+}
+
+VideoCaptureImplManager::Device::Device() : vc(NULL) {}
+
+VideoCaptureImplManager::Device::Device(
+    VideoCaptureImpl* device,
+    media::VideoCapture::EventHandler* handler)
+    : vc(device) {
+  clients.push_front(handler);
+}
+
+VideoCaptureImplManager::Device::~Device() {}
+