Lazy-creates BluetoothAdapter in ExtensionBluetoothEventRouter (EBEE).

chrome/browser/extensions/bluetooth_event_router.cc

Index: chrome/browser/extensions/bluetooth_event_router.cc
diff --git a/chrome/browser/extensions/bluetooth_event_router.cc b/chrome/browser/extensions/bluetooth_event_router.cc
index d38db9e8b925a6438b7a199889ee2f576b1ea5dc..1df24a8bf4762e0600109f8cee35e8cc75df46e1 100644
--- a/chrome/browser/extensions/bluetooth_event_router.cc
+++ b/chrome/browser/extensions/bluetooth_event_router.cc
@@ -5,6 +5,7 @@
 #include "chrome/browser/extensions/bluetooth_event_router.h"
 
 #include <map>
+#include <string>
 
 #include "base/json/json_writer.h"
 #include "base/memory/ref_counted.h"
@@ -26,20 +27,47 @@ ExtensionBluetoothEventRouter::ExtensionBluetoothEventRouter(Profile* profile)
     : send_discovery_events_(false),
       responsible_for_discovery_(false),
       profile_(profile),
-      adapter_(device::BluetoothAdapterFactory::DefaultAdapter()),
+      adapter_(NULL),
+      num_event_listeners_(0),
       next_socket_id_(1) {
   DCHECK(profile_);
-  if (adapter_.get())
-    adapter_->AddObserver(this);
 }
 
 ExtensionBluetoothEventRouter::~ExtensionBluetoothEventRouter() {
   if (adapter_.get())

[bryeung, 2012/11/08 19:24:02]

I think the .get is actually not necessary

[youngki, 2012/11/09 05:12:52]

Done.

-    adapter_->RemoveObserver(this);
+    ReleaseAdapter();
 
   socket_map_.clear();
 }
 
+scoped_refptr<const device::BluetoothAdapter>
+ExtensionBluetoothEventRouter::adapter() {
+  return GetMutableAdapter();
+}
+
+scoped_refptr<device::BluetoothAdapter>
+ExtensionBluetoothEventRouter::GetMutableAdapter() {
+  if (adapter_.get())

[bryeung, 2012/11/08 19:24:02]

I don't think you need the .get()

I'll stop repeating this comment now :-)

[youngki, 2012/11/09 05:12:52]

Done.

+    return adapter_;
+
+  return GetDefaultAdapter();

[bryeung, 2012/11/08 19:24:02]

shouldn't this be initializing the adapter?

[youngki, 2012/11/09 05:12:52]

Maybe I am thinking too specifically on Windows Bluetooth adapter side, so let
me know if this is a bad decision for BluetoothEventRouter itself, but I don't
think we need to initialize the adapter (i.e. hold the reference to it) for the
following reasons:

1) If the adapter wasn't referenced anywhere, then this function will create an
adapter and return it with up-to-date bluetooth adapter info. So no need to hold
the reference in this case.

2) If the adapter is already referenced somewhere, then the adapter is already
likely to have an up-to-date (less than 500ms in windows circumstance) bluetooth
adapter info, so no need to hold a reference to it.

+}
+
+void ExtensionBluetoothEventRouter::InitializeAdapter() {

[bryeung, 2012/11/08 19:24:02]

is there a use case for having an adapter that has not been initialized?  Seems
like it would be safer to just move this code into GetMutableAdapater.

[youngki, 2012/11/09 05:12:52]

This is actually an helper method to not repeat the same two lines over and
over. Note that InitializeAdapter() is also called in RegisterSocket and
OnEventListenerAdded.

+  adapter_ = GetDefaultAdapter();
+  adapter_->AddObserver(this);
+}
+
+void ExtensionBluetoothEventRouter::ReleaseAdapter() {
+  adapter_->RemoveObserver(this);
+  adapter_ = NULL;
+}
+
+scoped_refptr<device::BluetoothAdapter>
+ExtensionBluetoothEventRouter::GetDefaultAdapter() const {
+  return device::BluetoothAdapterFactory::DefaultAdapter();

[bryeung, 2012/11/08 19:24:02]

why not put this inside of GetMutableAdapter and use that everywhere within this
class as well?

[youngki, 2012/11/09 05:12:52]

This is for unittest purpose. I want to override this method in the unittest so
that this method returns mock adapter instead.

+}
+
 int ExtensionBluetoothEventRouter::RegisterSocket(
     scoped_refptr<device::BluetoothSocket> socket) {
   // If there is a socket registered with the same fd, just return it's id
@@ -51,6 +79,9 @@ int ExtensionBluetoothEventRouter::RegisterSocket(
   }
   int return_id = next_socket_id_++;
   socket_map_[return_id] = socket;
+  if (!adapter_.get())
+    InitializeAdapter();
+
   return return_id;
 }
 
@@ -59,6 +90,9 @@ bool ExtensionBluetoothEventRouter::ReleaseSocket(int id) {
   if (socket_entry == socket_map_.end())
     return false;
   socket_map_.erase(socket_entry);
+  if (adapter_.get() && !IsAdapterNeeded())
+    ReleaseAdapter();
+
   return true;
 }
 
@@ -70,6 +104,38 @@ ExtensionBluetoothEventRouter::GetSocket(int id) {
   return socket_entry->second;
 }
 
+// static
+bool ExtensionBluetoothEventRouter::IsBluetoothEvent(
+    const std::string& event_name) {
+  return
+      event_name == extensions::event_names::kBluetoothOnAvailabilityChanged ||
+      event_name == extensions::event_names::kBluetoothOnDiscoveringChanged ||
+      event_name == extensions::event_names::kBluetoothOnPowerChanged;
+}
+
+bool ExtensionBluetoothEventRouter::IsAdapterNeeded() const {
+  return num_event_listeners_ > 0 || socket_map_.size() > 0;
+}
+
+void ExtensionBluetoothEventRouter::OnEventListenerAdded(
+    const std::string& event_name) {
+  if (IsBluetoothEvent(event_name)) {
+    num_event_listeners_++;
+    if (!adapter_.get())
+      InitializeAdapter();
+  }
+}
+
+void ExtensionBluetoothEventRouter::OnEventListenerRemoved(
+    const std::string& event_name) {
+  if (IsBluetoothEvent(event_name)) {
+    num_event_listeners_--;
+    DCHECK(num_event_listeners_ >= 0);
+    if (adapter_.get() && !IsAdapterNeeded())
+      ReleaseAdapter();
+  }
+}
+
 void ExtensionBluetoothEventRouter::SetResponsibleForDiscovery(
     bool responsible) {
   responsible_for_discovery_ = responsible;