[WebMIDI] Introduce UsbMidi{Input, Output}Stream.

content/browser/renderer_host/media/midi_host.cc

 // Copyright (c) 2013 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.
 
 #include "content/browser/renderer_host/media/midi_host.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/debug/trace_event.h"
 #include "base/process/process.h"
@@ skipping 17 matching lines @@
 // The total number of bytes which we're allowed to send to the OS
 // before knowing that they have been successfully sent.
 const size_t kMaxInFlightBytes = 10 * 1024 * 1024;  // 10 MB.
 
 // We keep track of the number of bytes successfully sent to
 // the hardware.  Every once in a while we report back to the renderer
 // the number of bytes sent since the last report. This threshold determines
 // how many bytes will be sent before reporting back to the renderer.
 const size_t kAcknowledgementThresholdBytes = 1024 * 1024;  // 1 MB.
 
-const uint8 kSysExMessage = 0xf0;
-const uint8 kEndOfSysExMessage = 0xf7;
-
 bool IsDataByte(uint8 data) {
   return (data & 0x80) == 0;
 }
 
 bool IsSystemRealTimeMessage(uint8 data) {
   return 0xf8 <= data && data <= 0xff;
 }
 
 }  // namespace
 
+using media::kSystemExclusiveByte;
+using media::kSystemExclusiveEndByte;

[Takashi Toyoshima, 2014/01/15 12:08:40]

EOX or End of SysEx is an official name and I'm using EndOfSysEx in blink.

[yhirano, 2014/01/15 13:25:42]

Done.

+
 MIDIHost::MIDIHost(int renderer_process_id, media::MIDIManager* midi_manager)
     : renderer_process_id_(renderer_process_id),
       has_sys_ex_permission_(false),
       midi_manager_(midi_manager),
       sent_bytes_in_flight_(0),
       bytes_sent_since_last_acknowledgement_(0) {
 }
 
 MIDIHost::~MIDIHost() {
   if (midi_manager_)
@@ skipping 51 matching lines @@
   if (!midi_manager_)
     return;
 
   if (data.empty())
     return;
 
   // Blink running in a renderer checks permission to raise a SecurityError
   // in JavaScript. The actual permission check for security purposes
   // happens here in the browser process.
   if (!has_sys_ex_permission_ &&
-      (std::find(data.begin(), data.end(), kSysExMessage) != data.end())) {
+      (std::find(data.begin(), data.end(), kSystemExclusiveByte)
+       != data.end())) {
     RecordAction(base::UserMetricsAction("BadMessageTerminate_MIDI"));
     BadMessageReceived();
     return;
   }
 
   if (!IsValidWebMIDIData(data))
     return;
 
   base::AutoLock auto_lock(in_flight_lock_);
   // Sanity check that we won't send too much data.
@@ skipping 22 matching lines @@
   received_messages_queues_[port]->Add(data, length);
   std::vector<uint8> message;
   while (true) {
     received_messages_queues_[port]->Get(&message);
     if (message.empty())
       break;
 
     // MIDI devices may send a system exclusive messages even if the renderer
     // doesn't have a permission to receive it. Don't kill the renderer as
     // OnSendData() does.
-    if (message[0] == kSysExMessage && !has_sys_ex_permission_)
+    if (message[0] == kSystemExclusiveByte && !has_sys_ex_permission_)
       continue;
 
     // Send to the renderer.
     Send(new MIDIMsg_DataReceived(port, message, timestamp));
   }
 }
 
 void MIDIHost::AccumulateMIDIBytesSent(size_t n) {
   {
     base::AutoLock auto_lock(in_flight_lock_);
@@ skipping 21 matching lines @@
     const uint8 current = data[i];
     if (IsSystemRealTimeMessage(current))
       continue;  // Real time message can be placed at any point.
     if (waiting_data_length > 0) {
       if (!IsDataByte(current))
         return false;  // Error: |current| should have been data byte.
       --waiting_data_length;
       continue;  // Found data byte as expected.
     }
     if (in_sysex) {
-      if (data[i] == kEndOfSysExMessage)
+      if (data[i] == kSystemExclusiveEndByte)
         in_sysex = false;
       else if (!IsDataByte(current))
         return false;  // Error: |current| should have been data byte.
       continue;  // Found data byte as expected.
     }
-    if (current == kSysExMessage) {
+    if (current == kSystemExclusiveByte) {
       in_sysex = true;
       continue;  // Found SysEX
     }
     waiting_data_length = media::GetMIDIMessageLength(current);
     if (waiting_data_length == 0)
       return false;  // Error: |current| should have been a valid status byte.
     --waiting_data_length;  // Found status byte
   }
   return waiting_data_length == 0 && !in_sysex;
 }
 
 }  // namespace content