Implement Web MIDI API back-end

This involves browser-side support and IPC for sending and receiving
MIDI messages.  Initially support for OSX is included.

BUG=163795
R=palmer@chromium.org, piman@chromium.org, scherkus@chromium.org

Review URL: https://codereview.chromium.org/16025005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@207983 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 161 insertions, 0 deletions

diff --git a/content/browser/renderer_host/media/midi_host.cc b/content/browser/renderer_host/media/midi_host.cc
new file mode 100644
index 0000000..56f4099
--- /dev/null
+++ b/content/browser/renderer_host/media/midi_host.cc
@@ -0,0 +1,99 @@
+// 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.h"
+#include "content/browser/browser_main_loop.h"
+#include "content/browser/media/media_internals.h"
+#include "content/common/media/midi_messages.h"
+#include "content/public/browser/content_browser_client.h"
+#include "content/public/browser/media_observer.h"
+#include "media/midi/midi_manager.h"
+
+using media::MIDIManager;
+using media::MIDIPortInfoList;
+
+namespace content {
+
+MIDIHost::MIDIHost(media::MIDIManager* midi_manager)
+    : midi_manager_(midi_manager) {
+}
+
+MIDIHost::~MIDIHost() {
+  if (midi_manager_)
+    midi_manager_->ReleaseAccess(this);
+}
+
+void MIDIHost::OnChannelClosing() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  BrowserMessageFilter::OnChannelClosing();
+}
+
+void MIDIHost::OnDestruct() const {
+  BrowserThread::DeleteOnIOThread::Destruct(this);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// IPC Messages handler
+bool MIDIHost::OnMessageReceived(const IPC::Message& message,
+                                 bool* message_was_ok) {
+  bool handled = true;
+  IPC_BEGIN_MESSAGE_MAP_EX(MIDIHost, message, *message_was_ok)
+    IPC_MESSAGE_HANDLER(MIDIHostMsg_RequestAccess, OnRequestAccess)
+    IPC_MESSAGE_HANDLER(MIDIHostMsg_SendData, OnSendData)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP_EX()
+
+  return handled;
+}
+
+void MIDIHost::OnRequestAccess(int client_id, int access) {
+  MIDIPortInfoList input_ports;
+  MIDIPortInfoList output_ports;
+
+  // Ask permission and register to receive MIDI data.
+  bool approved = false;
+  if (midi_manager_) {
+    approved = midi_manager_->RequestAccess(this, access);
+    if (approved) {
+      input_ports = midi_manager_->input_ports();
+      output_ports = midi_manager_->output_ports();
+    }
+  }
+
+  Send(new MIDIMsg_AccessApproved(
+       client_id,
+       access,
+       approved,
+       input_ports,
+       output_ports));
+}
+
+void MIDIHost::OnSendData(int port,
+                          const std::vector<uint8>& data,
+                          double timestamp) {
+  // TODO(crogers): we need to post this to a dedicated thread for
+  // sending MIDI. For now, we will not implement the sending of MIDI data.
+  NOTIMPLEMENTED();
+  // if (midi_manager_)
+  //   midi_manager_->SendMIDIData(port, data.data(), data.size(), timestamp);
+}
+
+void MIDIHost::ReceiveMIDIData(
+    int port_index,
+    const uint8* data,
+    size_t length,
+    double timestamp) {
+  TRACE_EVENT0("midi", "MIDIHost::ReceiveMIDIData");
+  // Send to the renderer.
+  std::vector<uint8> v(data, data + length);
+  Send(new MIDIMsg_DataReceived(port_index, v, timestamp));
+}
+
+}  // namespace content
diff --git a/content/browser/renderer_host/media/midi_host.h b/content/browser/renderer_host/media/midi_host.h
new file mode 100644
index 0000000..e46ed53
--- /dev/null
+++ b/content/browser/renderer_host/media/midi_host.h
@@ -0,0 +1,62 @@
+// 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.
+
+#ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_MIDI_HOST_H_
+#define CONTENT_BROWSER_RENDERER_HOST_MEDIA_MIDI_HOST_H_
+
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "content/common/content_export.h"
+#include "content/public/browser/browser_message_filter.h"
+#include "content/public/browser/browser_thread.h"
+#include "media/midi/midi_manager.h"
+
+namespace media {
+class MIDIManager;
+}
+
+namespace content {
+
+class CONTENT_EXPORT MIDIHost
+    : public BrowserMessageFilter,
+      public media::MIDIManagerClient {
+ public:
+  // Called from UI thread from the owner of this object.
+  MIDIHost(media::MIDIManager* midi_manager);
+
+  // BrowserMessageFilter implementation.
+  virtual void OnChannelClosing() OVERRIDE;
+  virtual void OnDestruct() const OVERRIDE;
+  virtual bool OnMessageReceived(const IPC::Message& message,
+                                 bool* message_was_ok) OVERRIDE;
+
+  // MIDIManagerClient implementation.
+  virtual void ReceiveMIDIData(
+      int port_index,
+      const uint8* data,
+      size_t length,
+      double timestamp) OVERRIDE;
+
+  // Request access to MIDI hardware.
+  void OnRequestAccess(int client_id, int access);
+
+  // Data to be sent to a MIDI output port.
+  void OnSendData(int port,
+                  const std::vector<uint8>& data,
+                  double timestamp);
+
+ private:
+  friend class base::DeleteHelper<MIDIHost>;
+  friend class BrowserThread;
+
+  virtual ~MIDIHost();
+
+  media::MIDIManager* const midi_manager_;
+
+  DISALLOW_COPY_AND_ASSIGN(MIDIHost);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_MIDI_HOST_H_