Add an Observer interface to UsbService for device add/remove.

device/usb/usb_device_impl.cc

 // 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.
 
 #include "device/usb/usb_device_impl.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/location.h"
@@ skipping 86 matching lines @@
     case LIBUSB_ISO_USAGE_TYPE_IMPLICIT:
       return USB_USAGE_EXPLICIT_FEEDBACK;
     default:
       NOTREACHED();
       return USB_USAGE_DATA;
   }
 }
 
 }  // namespace
 
-UsbDevice::UsbDevice(uint16 vendor_id, uint16 product_id, uint32 unique_id)
-    : vendor_id_(vendor_id), product_id_(product_id), unique_id_(unique_id) {
-}
-
-UsbDevice::~UsbDevice() {
-}
-
-void UsbDevice::NotifyDisconnect() {
-  FOR_EACH_OBSERVER(Observer, observer_list_, OnDisconnect(this));
-}
-
 UsbDeviceImpl::UsbDeviceImpl(
     scoped_refptr<UsbContext> context,
     scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner,
     PlatformUsbDevice platform_device,
     uint16 vendor_id,
     uint16 product_id,
     uint32 unique_id)
     : UsbDevice(vendor_id, product_id, unique_id),
       platform_device_(platform_device),
       current_configuration_cached_(false),
@@ skipping 49 matching lines @@
       }
       break;
     }
   }
 #else
   strings_cached_ = false;
 #endif
 }
 
 UsbDeviceImpl::~UsbDeviceImpl() {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  for (HandlesVector::iterator it = handles_.begin(); it != handles_.end();
-       ++it) {
-    (*it)->InternalClose();
-  }
-  STLClearObject(&handles_);
+  // The destructor must be safe to call from any thread.
   libusb_unref_device(platform_device_);
 }
 
 #if defined(OS_CHROMEOS)
 
 void UsbDeviceImpl::RequestUsbAccess(
     int interface_id,
     const base::Callback<void(bool success)>& callback) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
@@ skipping 167 matching lines @@
     CacheStrings();
   }
 #endif
 
   *serial_number = serial_number_;
   return !serial_number_.empty();
 }
 
 void UsbDeviceImpl::OnDisconnect() {
   DCHECK(thread_checker_.CalledOnValidThread());
+
+  // Swap the list of handles into a local variable because closing all open
+  // handles may release the last reference to this object.
   HandlesVector handles;
   swap(handles, handles_);
-  for (HandlesVector::iterator it = handles.begin(); it != handles.end(); ++it)
-    (*it)->InternalClose();
+
+  for (const scoped_refptr<UsbDeviceHandleImpl>& handle : handles_) {
+    handle->InternalClose();
+  }
 }
 
 #if !defined(USE_UDEV)
 void UsbDeviceImpl::CacheStrings() {
   DCHECK(thread_checker_.CalledOnValidThread());
   // This is a non-blocking call as libusb has the descriptor in memory.
   libusb_device_descriptor desc;
   const int rv = libusb_get_device_descriptor(platform_device_, &desc);
   if (rv == LIBUSB_SUCCESS) {
     scoped_refptr<UsbDeviceHandle> device_handle = Open();
@@ skipping 13 matching lines @@
     }
   } else {
     VLOG(1) << "Failed to read device descriptor to cache string descriptors: "
             << ConvertPlatformUsbErrorToString(rv);
   }
   strings_cached_ = true;
 }
 #endif  // !defined(USE_UDEV)
 
 }  // namespace device