Web MIDI: minimum support for Linux and Chrome OS (reland)

This change enables Web MIDI API on Linux and Chrome OS.
Only Sending functionality works with this first experimental change.

BUG=303601
TBR=scherkus@chromium.org
NOTRY=true

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=241524

Review URL: https://codereview.chromium.org/111443005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242871 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/about_flags.cc

@@ -1678,7 +1678,7 @@ const Experiment kExperiments[] = {
     "enable-web-midi",
     IDS_FLAGS_ENABLE_WEB_MIDI_NAME,
     IDS_FLAGS_ENABLE_WEB_MIDI_DESCRIPTION,
-    kOsMac | kOsWin | kOsAndroid,
+    kOsMac | kOsWin | kOsLinux | kOsCrOS | kOsAndroid,
     SINGLE_VALUE_TYPE(switches::kEnableWebMIDI)
   },
   {

media/media.gyp

@@ -408,6 +408,8 @@
         'filters/wsola_internals.h',
         'midi/midi_manager.cc',
         'midi/midi_manager.h',
+        'midi/midi_manager_linux.cc',
+        'midi/midi_manager_linux.h',
         'midi/midi_manager_mac.cc',
         'midi/midi_manager_mac.h',
         'midi/midi_message_queue.cc',

media/midi/midi_manager.cc

@@ -9,8 +9,8 @@
 
 namespace media {
 
-#if !defined(OS_MACOSX) && !defined(OS_WIN)
-// TODO(crogers): implement MIDIManager for other platforms.
+#if defined(OS_ANDROID) || defined(OS_IOS)
+// TODO(toyoshim): implement MIDIManager for other platforms.
 MIDIManager* MIDIManager::Create() {
   return new MIDIManager;
 }

media/midi/midi_manager_linux.cc

@@ -0,0 +1,169 @@
+// 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.
+
+#include "media/midi/midi_manager_linux.h"
+
+#include <alsa/asoundlib.h>
+
+#include "base/bind.h"
+#include "base/debug/trace_event.h"
+#include "base/logging.h"
+#include "base/memory/ref_counted.h"
+#include "base/message_loop/message_loop.h"
+#include "base/strings/stringprintf.h"
+#include "base/threading/thread.h"
+#include "media/midi/midi_port_info.h"
+
+namespace media {
+namespace {
+const char kUnknown[] = "[unknown]";
+}  // namespace
+
+class MIDIManagerLinux::MIDIDeviceInfo
+    : public base::RefCounted<MIDIDeviceInfo> {
+ public:
+  MIDIDeviceInfo(MIDIManagerLinux* manager,
+                 const std::string& card,
+                 const snd_rawmidi_info_t* midi,
+                 int device) {
+    opened_ = !snd_rawmidi_open(&midi_in_, &midi_out_, card.c_str(), 0);
+    if (!opened_)
+      return;
+
+    const std::string name = snd_rawmidi_info_get_name(midi);
+    const std::string id = base::StringPrintf("%s:%d", card.c_str(), device);
+    port_info_ = MIDIPortInfo(id, kUnknown, name, kUnknown);
+  }
+
+  void Send(MIDIManagerClient* client, const std::vector<uint8>& data) {
+    ssize_t result = snd_rawmidi_write(
+        midi_out_, reinterpret_cast<const void*>(&data[0]), data.size());
+    if (static_cast<size_t>(result) != data.size()) {
+      // TODO(toyoshim): Disconnect and reopen the device.
+      LOG(ERROR) << "snd_rawmidi_write fails: " << strerror(-result);
+    }
+    base::MessageLoop::current()->PostTask(
+        FROM_HERE,
+        base::Bind(&MIDIManagerClient::AccumulateMIDIBytesSent,
+                   base::Unretained(client), data.size()));
+  }
+
+  const MIDIPortInfo& GetMIDIPortInfo() const { return port_info_; }
+  bool IsOpened() const { return opened_; }
+
+ private:
+  friend class base::RefCounted<MIDIDeviceInfo>;
+  virtual ~MIDIDeviceInfo() {
+    if (opened_) {
+      snd_rawmidi_close(midi_in_);
+      snd_rawmidi_close(midi_out_);
+    }
+  }
+
+  bool opened_;
+  MIDIPortInfo port_info_;
+  snd_rawmidi_t* midi_in_;
+  snd_rawmidi_t* midi_out_;
+
+  DISALLOW_COPY_AND_ASSIGN(MIDIDeviceInfo);
+};
+
+MIDIManagerLinux::MIDIManagerLinux()
+    : send_thread_("MIDISendThread") {
+}
+
+bool MIDIManagerLinux::Initialize() {
+  // TODO(toyoshim): Make Initialize() asynchronous.
+  TRACE_EVENT0("midi", "MIDIManagerMac::Initialize");
+
+  // Enumerate only hardware MIDI devices because software MIDIs running in
+  // the browser process is not secure.
+  snd_ctl_card_info_t* card;
+  snd_rawmidi_info_t* midi_out;
+  snd_rawmidi_info_t* midi_in;
+  snd_ctl_card_info_alloca(&card);
+  snd_rawmidi_info_alloca(&midi_out);
+  snd_rawmidi_info_alloca(&midi_in);
+  for (int index = -1; !snd_card_next(&index) && index >= 0; ) {
+    const std::string id = base::StringPrintf("hw:CARD=%i", index);
+    snd_ctl_t* handle;
+    int err = snd_ctl_open(&handle, id.c_str(), 0);
+    if (err != 0) {
+      DLOG(ERROR) << "snd_ctl_open fails: " << snd_strerror(err);
+      continue;
+    }
+    err = snd_ctl_card_info(handle, card);
+    if (err != 0) {
+      DLOG(ERROR) << "snd_ctl_card_info fails: " << snd_strerror(err);
+      snd_ctl_close(handle);
+      continue;
+    }
+    for (int device = -1;
+        !snd_ctl_rawmidi_next_device(handle, &device) && device >= 0; ) {
+      bool output;
+      bool input;
+      snd_rawmidi_info_set_device(midi_out, device);
+      snd_rawmidi_info_set_subdevice(midi_out, 0);
+      snd_rawmidi_info_set_stream(midi_out, SND_RAWMIDI_STREAM_OUTPUT);
+      output = snd_ctl_rawmidi_info(handle, midi_out) == 0;
+      snd_rawmidi_info_set_device(midi_in, device);
+      snd_rawmidi_info_set_subdevice(midi_in, 0);
+      snd_rawmidi_info_set_stream(midi_in, SND_RAWMIDI_STREAM_INPUT);
+      input = snd_ctl_rawmidi_info(handle, midi_in) == 0;
+      if (!output && !input)
+        continue;
+      scoped_refptr<MIDIDeviceInfo> port =
+          new MIDIDeviceInfo(this, id, output ? midi_out : midi_in, device);
+      if (!port->IsOpened()) {
+        DLOG(ERROR) << "MIDIDeviceInfo open fails";
+        continue;
+      }
+      if (input) {
+        in_devices_.push_back(port);
+        AddInputPort(port->GetMIDIPortInfo());
+      }
+      if (output) {
+        out_devices_.push_back(port);
+        AddOutputPort(port->GetMIDIPortInfo());
+      }
+    }
+    snd_ctl_close(handle);
+  }
+  return true;
+}
+
+MIDIManagerLinux::~MIDIManagerLinux() {
+  send_thread_.Stop();
+}
+
+void MIDIManagerLinux::DispatchSendMIDIData(MIDIManagerClient* client,
+                                            uint32 port_index,
+                                            const std::vector<uint8>& data,
+                                            double timestamp) {
+  if (out_devices_.size() <= port_index)
+    return;
+
+  base::TimeDelta delay;
+  if (timestamp != 0.0) {
+    base::TimeTicks time_to_send =
+        base::TimeTicks() + base::TimeDelta::FromMicroseconds(
+            timestamp * base::Time::kMicrosecondsPerSecond);
+    delay = std::max(time_to_send - base::TimeTicks::Now(), base::TimeDelta());
+  }
+
+  if (!send_thread_.IsRunning())
+    send_thread_.Start();
+
+  scoped_refptr<MIDIDeviceInfo> device = out_devices_[port_index];
+  send_thread_.message_loop()->PostDelayedTask(
+      FROM_HERE,
+      base::Bind(&MIDIDeviceInfo::Send, device, client, data),
+      delay);
+}
+
+MIDIManager* MIDIManager::Create() {
+  return new MIDIManagerLinux();
+}
+
+}  // namespace media

media/midi/midi_manager_linux.h

@@ -0,0 +1,39 @@
+// 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 MEDIA_MIDI_MIDI_MANAGER_LINUX_H_
+#define MEDIA_MIDI_MIDI_MANAGER_LINUX_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/threading/thread.h"
+#include "media/midi/midi_manager.h"
+
+namespace media {
+
+class MIDIManagerLinux : public MIDIManager {
+ public:
+  MIDIManagerLinux();
+  virtual ~MIDIManagerLinux();
+
+  // MIDIManager implementation.
+  virtual bool Initialize() OVERRIDE;
+  virtual void DispatchSendMIDIData(MIDIManagerClient* client,
+                                    uint32 port_index,
+                                    const std::vector<uint8>& data,
+                                    double timestamp) OVERRIDE;
+
+ private:
+  class MIDIDeviceInfo;
+  std::vector<scoped_refptr<MIDIDeviceInfo> > in_devices_;
+  std::vector<scoped_refptr<MIDIDeviceInfo> > out_devices_;
+  base::Thread send_thread_;
+  DISALLOW_COPY_AND_ASSIGN(MIDIManagerLinux);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_MIDI_MIDI_MANAGER_LINUX_H_