Fix missing callback chaining in UsbService.

chrome/browser/usb/usb_service.h

 // Copyright (c) 2012 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 CHROME_BROWSER_USB_USB_SERVICE_H_
 #define CHROME_BROWSER_USB_USB_SERVICE_H_
 
 #include <map>
 #include <utility>
 #include <vector>
@@ skipping 15 matching lines @@
  public:
   UsbService();
   virtual ~UsbService();
 
   // Cleanup must be invoked before the service is destroyed. It interrupts the
   // event handling thread and disposes of open devices.
   void Cleanup();
 
   // Find all of the devices attached to the system that are identified by
   // |vendor_id| and |product_id|, inserting them into |devices|. Clears
-  // |devices| before use.
+  // |devices| before use. Calls |callback| once |devices| is populated.
   void FindDevices(const uint16 vendor_id,
                    const uint16 product_id,
-                   std::vector<scoped_refptr<UsbDevice> >* devices);
+                   std::vector<scoped_refptr<UsbDevice> >* devices,
+                   const base::Callback<void()>& callback);
 
   // This function should not be called by normal code. It is invoked by a
   // UsbDevice's Close function and disposes of the associated platform handle.
   void CloseDevice(scoped_refptr<UsbDevice> device);
 
  private:
   // RefCountedPlatformUsbDevice takes care of managing the underlying reference
   // count of a single PlatformUsbDevice. This allows us to construct things
   // like vectors of RefCountedPlatformUsbDevices and not worry about having to
   // explicitly unreference them after use.
@@ skipping 16 matching lines @@
                             const uint16 vendor_id,
                             const uint16 product_id);
 
   // FindDevicesImpl is called by FindDevices on ChromeOS after the permission
   // broker has signalled that permission has been granted to access the
   // underlying device nodes. On other platforms, it is called directly by
   // FindDevices.
   void FindDevicesImpl(const uint16 vendor_id,
                        const uint16 product_id,
                        std::vector<scoped_refptr<UsbDevice> >* devices,
+                       const base::Callback<void()>& callback,
                        bool success);
 
   // Populates |output| with the result of enumerating all attached USB devices.
   void EnumerateDevices(DeviceVector* output);
 
   // If a UsbDevice wrapper corresponding to |device| has already been created,
   // returns it. Otherwise, opens the device, creates a wrapper, and associates
   // the wrapper with the device internally.
   UsbDevice* LookupOrCreateDevice(PlatformUsbDevice device);
 
   PlatformUsbContext context_;
   UsbEventHandler* event_handler_;
 
   // The devices_ map contains scoped_refptrs to all open devices, indicated by
   // their vendor and product id. This allows for reusing an open device without
   // creating another platform handle for it.
   typedef std::map<PlatformUsbDevice, scoped_refptr<UsbDevice> > DeviceMap;
   DeviceMap devices_;
 
   DISALLOW_COPY_AND_ASSIGN(UsbService);
 };
 
 #endif  // CHROME_BROWSER_USB_USB_SERVICE_H_