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

extensions/browser/api/hid/hid_api.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 EXTENSIONS_BROWSER_API_HID_HID_API_H_
 #define EXTENSIONS_BROWSER_API_HID_HID_API_H_
 
 #include <string>
 
 #include "base/memory/ref_counted.h"
@@ skipping 94 matching lines @@
 
   HidReceiveFunction();
 
  protected:
   virtual bool Prepare() OVERRIDE;
   virtual void AsyncWorkStart() OVERRIDE;
 
  private:
   virtual ~HidReceiveFunction();
 
-  void OnFinished(bool success, size_t bytes);
+  void OnFinished(bool success,
+                  scoped_refptr<net::IOBuffer> buffer,
+                  size_t size);
 
-  bool has_report_id_;
-  scoped_refptr<net::IOBufferWithSize> buffer_;
   scoped_ptr<core_api::hid::Receive::Params> parameters_;
 
   DISALLOW_COPY_AND_ASSIGN(HidReceiveFunction);
 };
 
 class HidSendFunction : public HidAsyncApiFunction {
  public:
   DECLARE_EXTENSION_FUNCTION("hid.send", HID_SEND);
 
   HidSendFunction();
 
  protected:
   virtual bool Prepare() OVERRIDE;
   virtual void AsyncWorkStart() OVERRIDE;
 
  private:
   virtual ~HidSendFunction();
 
-  void OnFinished(bool success, size_t bytes);
+  void OnFinished(bool success);
 
   scoped_ptr<core_api::hid::Send::Params> parameters_;
 
   DISALLOW_COPY_AND_ASSIGN(HidSendFunction);
 };
 
 class HidReceiveFeatureReportFunction : public HidAsyncApiFunction {
  public:
   DECLARE_EXTENSION_FUNCTION("hid.receiveFeatureReport",
                              HID_RECEIVEFEATUREREPORT);
 
   HidReceiveFeatureReportFunction();
 
  protected:
   virtual bool Prepare() OVERRIDE;
   virtual void AsyncWorkStart() OVERRIDE;
 
  private:
   virtual ~HidReceiveFeatureReportFunction();
 
-  void OnFinished(bool success, size_t bytes);
+  void OnFinished(bool success,
+                  scoped_refptr<net::IOBuffer> buffer,
+                  size_t size);
 
-  scoped_refptr<net::IOBufferWithSize> buffer_;
   scoped_ptr<core_api::hid::ReceiveFeatureReport::Params> parameters_;
 
   DISALLOW_COPY_AND_ASSIGN(HidReceiveFeatureReportFunction);
 };
 
 class HidSendFeatureReportFunction : public HidAsyncApiFunction {
  public:
   DECLARE_EXTENSION_FUNCTION("hid.sendFeatureReport", HID_SENDFEATUREREPORT);
 
   HidSendFeatureReportFunction();
 
  protected:
   virtual bool Prepare() OVERRIDE;
   virtual void AsyncWorkStart() OVERRIDE;
 
  private:
   virtual ~HidSendFeatureReportFunction();
 
-  void OnFinished(bool success, size_t bytes);
+  void OnFinished(bool success);
 
   scoped_ptr<core_api::hid::SendFeatureReport::Params> parameters_;
 
   DISALLOW_COPY_AND_ASSIGN(HidSendFeatureReportFunction);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_API_HID_HID_API_H_