Don't pass buffers to HidConnection::Read because it knows the size.

device/hid/hid_connection_mac.h

 // Copyright (c) 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_CONNECTION_MAC_H_
 #define DEVICE_HID_HID_CONNECTION_MAC_H_
 
 #include <CoreFoundation/CoreFoundation.h>
 #include <IOKit/hid/IOHIDManager.h>
 
@@ skipping 11 matching lines @@
 class IOBuffer;
 }
 
 namespace device {
 
 class HidConnectionMac : public HidConnection {
  public:
   explicit HidConnectionMac(HidDeviceInfo device_info);
 
   // HidConnection implementation.
-  virtual void PlatformRead(scoped_refptr<net::IOBufferWithSize> buffer,
-                            const IOCallback& callback) OVERRIDE;
-  virtual void PlatformWrite(uint8_t report_id,
-                             scoped_refptr<net::IOBufferWithSize> buffer,
-                             const IOCallback& callback) OVERRIDE;
-  virtual void PlatformGetFeatureReport(
-      uint8_t report_id,
-      scoped_refptr<net::IOBufferWithSize> buffer,
-      const IOCallback& callback) OVERRIDE;
+  virtual void PlatformRead(const ReadCallback& callback) OVERRIDE;
+  virtual void PlatformWrite(scoped_refptr<net::IOBuffer> buffer,
+                             size_t size,
+                             const WriteCallback& callback) OVERRIDE;
+  virtual void PlatformGetFeatureReport(uint8_t report_id,
+                                        const ReadCallback& callback) OVERRIDE;
   virtual void PlatformSendFeatureReport(
-      uint8_t report_id,
-      scoped_refptr<net::IOBufferWithSize> buffer,
-      const IOCallback& callback) OVERRIDE;
+      scoped_refptr<net::IOBuffer> buffer,
+      size_t size,
+      const WriteCallback& callback) OVERRIDE;
 
  private:
   virtual ~HidConnectionMac();
 
   static void InputReportCallback(void* context,
                                   IOReturn result,
                                   void* sender,
                                   IOHIDReportType type,
                                   uint32_t report_id,
                                   uint8_t* report_bytes,
                                   CFIndex report_length);
 
   void WriteReport(IOHIDReportType type,
-                   uint8_t report_id,
-                   scoped_refptr<net::IOBufferWithSize> buffer,
-                   const IOCallback& callback);
+                   scoped_refptr<net::IOBuffer> buffer,
+                   size_t size,
+                   const WriteCallback& callback);
 
   void Flush();
   void ProcessInputReport(scoped_refptr<net::IOBufferWithSize> buffer);
   void ProcessReadQueue();
 
   base::ScopedCFTypeRef<IOHIDDeviceRef> device_;
   scoped_refptr<base::MessageLoopProxy> message_loop_;
-  scoped_ptr<uint8_t, base::FreeDeleter> inbound_buffer_;
+  scoped_ptr<uint8_t[]> inbound_buffer_;
 
   std::queue<PendingHidReport> pending_reports_;
   std::queue<PendingHidRead> pending_reads_;
 
   DISALLOW_COPY_AND_ASSIGN(HidConnectionMac);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_HID_HID_CONNECTION_MAC_H_