Check USB device path access when prompting users to select a device.

device/usb/usb_device.h

 // 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_USB_USB_DEVICE_H_
 #define DEVICE_USB_USB_DEVICE_H_
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/strings/string16.h"
 
 namespace device {
 
 class UsbDeviceHandle;
 struct UsbConfigDescriptor;
 
 // A UsbDevice object represents a detected USB device, providing basic
 // information about it. For further manipulation of the device, a
 // UsbDeviceHandle must be created from Open() method.
 class UsbDevice : public base::RefCountedThreadSafe<UsbDevice> {
  public:
+  typedef base::Callback<void(bool success)> ResultCallback;
+
   // Accessors to basic information.
   uint16 vendor_id() const { return vendor_id_; }
   uint16 product_id() const { return product_id_; }
   uint32 unique_id() const { return unique_id_; }
 
-#if defined(OS_CHROMEOS)
-  // On ChromeOS, if an interface of a claimed device is not claimed, the
-  // permission broker can change the owner of the device so that the unclaimed
-  // interfaces can be used. If this argument is missing, permission broker will
-  // not be used and this method fails if the device is claimed.
-  virtual void RequestUsbAccess(
-      int interface_id,
-      const base::Callback<void(bool success)>& callback) = 0;
-#endif  // OS_CHROMEOS
+  // On ChromeOS the permission_broker service is used to change the ownership
+  // of USB device nodes so that Chrome can open them. On other platforms these
+  // functions are no-ops and always return true.
+  virtual void CheckUsbAccess(const ResultCallback& callback);
+
+  // Like CheckUsbAccess but actually changes the ownership of the device node.
+  virtual void RequestUsbAccess(int interface_id,
+                                const ResultCallback& callback);
 
   // Creates a UsbDeviceHandle for further manipulation.
   // Blocking method. Must be called on FILE thread.
   virtual scoped_refptr<UsbDeviceHandle> Open() = 0;
 
   // Explicitly closes a device handle. This method will be automatically called
   // by the destructor of a UsbDeviceHandle as well.
   // Closing a closed handle is a safe
   // Blocking method. Must be called on FILE thread.
   virtual bool Close(scoped_refptr<UsbDeviceHandle> handle) = 0;
@@ skipping 12 matching lines @@
   // string. This is a blocking method and must be called on FILE thread.
   // TODO(reillyg): Make this available from the UI thread. crbug.com/427985
   virtual bool GetProduct(base::string16* product) = 0;
 
   // Gets the serial number string of the device, or returns false and an empty
   // string. This is a blocking method and must be called on FILE thread.
   // TODO(reillyg): Make this available from the UI thread. crbug.com/427985
   virtual bool GetSerialNumber(base::string16* serial) = 0;
 
  protected:
-  UsbDevice(uint16 vendor_id, uint16 product_id, uint32 unique_id)
-      : vendor_id_(vendor_id), product_id_(product_id), unique_id_(unique_id) {}
-  virtual ~UsbDevice() {}
+  UsbDevice(uint16 vendor_id, uint16 product_id, uint32 unique_id);
+  virtual ~UsbDevice();
 
  private:
   friend class base::RefCountedThreadSafe<UsbDevice>;
 
   const uint16 vendor_id_;
   const uint16 product_id_;
   const uint32 unique_id_;
 
   DISALLOW_COPY_AND_ASSIGN(UsbDevice);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_USB_USB_DEVICE_H_