MidiManagerAlsa: Enable manufacturer again, now with hotplug

media/midi/midi_manager_alsa.h

Index: media/midi/midi_manager_alsa.h
diff --git a/media/midi/midi_manager_alsa.h b/media/midi/midi_manager_alsa.h
index db78dff300fcfa188028674457838aaff7c22d55..e8b2f6b631f8fc9555bf33b10fc2094761772462 100644
--- a/media/midi/midi_manager_alsa.h
+++ b/media/midi/midi_manager_alsa.h
@@ -41,6 +41,9 @@ class MIDI_EXPORT MidiManagerAlsa final : public MidiManager {
   FRIEND_TEST_ALL_PREFIXES(MidiManagerAlsaTest, ExtractManufacturer);
   FRIEND_TEST_ALL_PREFIXES(MidiManagerAlsaTest, ToMidiPortState);
 
+  class AlsaCard;
+  typedef std::map<int, AlsaCard*> AlsaCardMap;
+
   class MidiPort {
    public:
     enum class Type { kInput, kOutput };
@@ -210,7 +213,10 @@ class MIDI_EXPORT MidiManagerAlsa final : public MidiManager {
                    bool midi);
     void PortExit(int client_id, int port_id);
     snd_seq_client_type_t ClientType(int client_id) const;
-    scoped_ptr<TemporaryMidiPortState> ToMidiPortState();
+    scoped_ptr<TemporaryMidiPortState> ToMidiPortState(
+        const AlsaCardMap& alsa_cards);
+
+    int card_client_count() { return card_client_count_; }
 
    private:
     class Port {
@@ -259,20 +265,63 @@ class MIDI_EXPORT MidiManagerAlsa final : public MidiManager {
     ClientMap clients_;
     STLValueDeleter<ClientMap> clients_deleter_;
 
+    // This is the current number of clients we know about that have
+    // cards. When this number matches alsa_card_midi_count_, we know
+    // we are in sync between ALSA and udev. Until then, we cannot generate
+    // MIDIConnectionEvents to web clients.
+    int card_client_count_;
+
     DISALLOW_COPY_AND_ASSIGN(AlsaSeqState);
   };
 
+  class AlsaCard {
+   public:
+    AlsaCard(udev_device* dev,
+             const std::string& alsa_name,
+             const std::string& alsa_longname,
+             const std::string& alsa_driver,
+             int midi_device_count);
+    ~AlsaCard();
+    const std::string alsa_name() const { return alsa_name_; }
+    const std::string alsa_longname() const { return alsa_longname_; }
+    const std::string manufacturer() const { return manufacturer_; }
+    const std::string alsa_driver() const { return alsa_driver_; }
+    int midi_device_count() const { return midi_device_count_; }
+    // Returns hardware path.
+    const std::string path() const;
+    // Returns the id we can use to try to match hardware across different
+    // paths.
+    const std::string id() const;
+
+   private:
+    FRIEND_TEST_ALL_PREFIXES(MidiManagerAlsaTest, ExtractManufacturer);
+
+    // Extracts the manufacturer using heuristics and a variety of sources.
+    static std::string ExtractManufacturerString(
+        const std::string& udev_id_vendor,
+        const std::string& udev_id_vendor_id,
+        const std::string& udev_id_vendor_from_database,
+        const std::string& alsa_name,
+        const std::string& alsa_longname);
+
+    std::string alsa_name_;
+    std::string alsa_longname_;
+    std::string manufacturer_;
+    std::string alsa_driver_;
+    std::string path_;
+    std::string bus_;
+    std::string serial_;
+    std::string vendor_id_;
+    std::string model_id_;
+    std::string usb_interface_num_;
+    int midi_device_count_;
+
+    DISALLOW_COPY_AND_ASSIGN(AlsaCard);
+  };
+
   typedef base::hash_map<int, uint32> SourceMap;
   typedef base::hash_map<uint32, int> OutPortMap;
 
-  // Extracts the manufacturer using heuristics and a variety of sources.
-  static std::string ExtractManufacturerString(
-      const std::string& udev_id_vendor,
-      const std::string& udev_id_vendor_id,
-      const std::string& udev_id_vendor_from_database,
-      const std::string& alsa_name,
-      const std::string& alsa_longname);
-
   // An internal callback that runs on MidiSendThread.
   void SendMidiData(uint32 port_index, const std::vector<uint8>& data);
 
@@ -284,6 +333,8 @@ class MIDI_EXPORT MidiManagerAlsa final : public MidiManager {
   void ProcessClientExitEvent(const snd_seq_addr_t& addr);
   void ProcessPortExitEvent(const snd_seq_addr_t& addr);
   void ProcessUdevEvent(udev_device* dev);
+  void AddCard(udev_device* dev);
+  void RemoveCard(int number);
 
   // Updates port_state_ and Web MIDI state from alsa_seq_state_.
   void UpdatePortStateAndGenerateEvents();
@@ -315,6 +366,16 @@ class MIDI_EXPORT MidiManagerAlsa final : public MidiManager {
   // Mapping from ALSA client:port to our index.
   SourceMap source_map_;
 
+  // Mapping from card to devices.
+  AlsaCardMap alsa_cards_;
+  STLValueDeleter<AlsaCardMap> alsa_cards_deleter_;
+
+  // This is the current count of midi devices across all cards we know
+  // about. When this number matches card_client_count_ in AlsaSeqState,
+  // we are safe to generate MIDIConnectionEvents. Otherwise we need to
+  // wait for our information from ALSA and udev to get back in sync.
+  int alsa_card_midi_count_;
+
   // ALSA event -> MIDI coder.
   snd_midi_event_t* decoder_;