Add a manifest property declaring USB printers supported by an app.

device/usb/usb_device_filter.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_FILTER_H_
 #define DEVICE_USB_USB_DEVICE_FILTER_H_
 
 #include <vector>
 
 #include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
 
 namespace base {
 class Value;
 }
 
 namespace device {
 
 class UsbDevice;
 
 class UsbDeviceFilter {
  public:
   UsbDeviceFilter();
   ~UsbDeviceFilter();
 
   void SetVendorId(uint16 vendor_id);
   void SetProductId(uint16 product_id);
   void SetInterfaceClass(uint8 interface_class);
   void SetInterfaceSubclass(uint8 interface_subclass);
   void SetInterfaceProtocol(uint8 interface_protocol);
 
   bool Matches(scoped_refptr<UsbDevice> device) const;
-  base::Value* ToValue() const;
+  scoped_ptr<base::Value> ToValue() const;
 
   static bool MatchesAny(scoped_refptr<UsbDevice> device,
                          const std::vector<UsbDeviceFilter>& filters);
 
  private:
   uint16 vendor_id_;
   uint16 product_id_;
   uint8 interface_class_;
   uint8 interface_subclass_;
   uint8 interface_protocol_;
   bool vendor_id_set_ : 1;
   bool product_id_set_ : 1;
   bool interface_class_set_ : 1;
   bool interface_subclass_set_ : 1;
   bool interface_protocol_set_ : 1;
 };
 
 }  // namespace device
 
 #endif  // DEVICE_USB_USB_DEVICE_FILTER_H_