Clean up HID backend and API.

device/hid/hid_service_mac.h

-// Copyright (c) 2014 The Chromium Authors. All rights reserved.
+// Copyright 2014 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.
 
 #ifndef DEVICE_HID_HID_SERVICE_MAC_H_
 #define DEVICE_HID_HID_SERVICE_MAC_H_
 
-#include <map>
+#include <CoreFoundation/CoreFoundation.h>
+#include <IOKit/hid/IOHIDManager.h>
+
 #include <string>
-#include <vector>
 
-#include "base/basictypes.h"
 #include "base/mac/foundation_util.h"
 #include "base/memory/ref_counted.h"
-#include "base/memory/singleton.h"
-#include "base/message_loop/message_loop.h"
-#include "base/strings/string16.h"
-#include "base/synchronization/waitable_event.h"
-#include "base/threading/thread.h"
-#include "base/threading/thread_checker.h"
-#include "build/build_config.h"
-#include "device/hid/hid_device_info.h"
+#include "device/hid/hid_platform_resource_bidi_map.h"
 #include "device/hid/hid_service.h"
 
-#include <CoreFoundation/CoreFoundation.h>
-#include <IOKit/hid/IOHIDManager.h>
+namespace base {
+class MessageLoopProxy;
+}
 
 namespace device {
 
 class HidConnection;
-class HidService;
 
 class HidServiceMac : public HidService {
  public:
   HidServiceMac();
 
-  virtual scoped_refptr<HidConnection> Connect(std::string device_id) OVERRIDE;
+  virtual scoped_refptr<HidConnection> Connect(HidDeviceId device_id) OVERRIDE;
 
  private:
   virtual ~HidServiceMac();
 
-  void ScheduleRunLoop();
-  void UnscheduleRunLoop();
+  void StartWatchingDevices();
+  void StopWatchingDevices();
 
   // Device changing callbacks.
   static void AddDeviceCallback(void* context,
                                 IOReturn result,
                                 void* sender,
-                                IOHIDDeviceRef ref);
+                                IOHIDDeviceRef hid_device);
   static void RemoveDeviceCallback(void* context,
                                    IOReturn result,
                                    void* sender,
-                                   IOHIDDeviceRef ref);
-  static HidServiceMac* InstanceFromContext(void* context);
-
-  IOHIDDeviceRef FindDevice(std::string id);
+                                   IOHIDDeviceRef hid_device);
 
   void Enumerate();
 
-  void PlatformAddDevice(IOHIDDeviceRef ref);
-  void PlatformRemoveDevice(IOHIDDeviceRef ref);
+  void PlatformAddDevice(IOHIDDeviceRef hid_device);
+  void PlatformRemoveDevice(IOHIDDeviceRef hid_device);
 
-  // The message loop this object belongs to.
+  // Platform HID Manager
+  base::ScopedCFTypeRef<IOHIDManagerRef> hid_manager_;
+
+  // The message loop for the thread on which this service was created.
   scoped_refptr<base::MessageLoopProxy> message_loop_;
 
-  // Platform HID Manager
-  base::ScopedCFTypeRef<IOHIDManagerRef> hid_manager_ref_;
-
-  // Enumeration thread.
-  scoped_ptr<base::Thread> enumeration_runloop_thread_;
-  CFRunLoopRef enumeration_runloop_;
-  base::WaitableEvent enumeration_runloop_init_;
-
-  bool available_;
+  // A 1:1 mapping between device IDs and IOHIDDeviceRefs.

[Mark Mentovai, 2014/02/21 17:48:18]

Why? Why go to the trouble of inventing our own handle scheme that we need to
deal with via a map, when all we really care about is (on Mac) the
IOHIDDeviceRef?

You can define HidDeviceId as

#if defined(OS_MACOSX)
typedef IOHIDDeviceRef HidDeviceId;
#else
typedef std::string HidDeviceId;
#endif

and, where possible, pass ’em around as HidDeviceId& to avoid string copies.

[Ken Rockot(use gerrit already), 2014/02/22 01:17:04]

Much simpler. I think the attachment to a consistent underlying type for the
device_id was really due to crossover from our primary intended use of this
interface (exposing a hid JS API to chrome apps). That's really a concern of the
higher-level API though, and it makes no sense to invent new handles at this
level. Thanks.

+  HidPlatformResourceBidiMap<IOHIDDeviceRef> platform_resource_map_;
 
   DISALLOW_COPY_AND_ASSIGN(HidServiceMac);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_HID_HID_SERVICE_MAC_H_