Changed DefaultAdapter to RunCallbackOnAdapterReady function.

chrome/browser/chromeos/system/ash_system_tray_delegate.cc

 // Copyright (c) 2012 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 "chrome/browser/chromeos/system/ash_system_tray_delegate.h"
 
 #include <algorithm>
 
 #include "ash/shell.h"
 #include "ash/shell_delegate.h"
@@ skipping 252 matching lines @@
     input_method::GetInputMethodManager()->AddObserver(this);
 
     system::TimezoneSettings::GetInstance()->AddObserver(this);
 
     if (SystemKeyEventListener::GetInstance())
       SystemKeyEventListener::GetInstance()->AddCapsLockObserver(this);
 
     network_icon_->SetResourceColorTheme(NetworkMenuIcon::COLOR_LIGHT);
     network_icon_dark_->SetResourceColorTheme(NetworkMenuIcon::COLOR_DARK);
 
-    bluetooth_adapter_ = device::BluetoothAdapterFactory::DefaultAdapter();
+    device::BluetoothAdapterFactory::RunCallbackOnAdapterReady(
+        base::Bind(&SystemTrayDelegate::InitializeOnAdapterReady,
+                   base::Unretained(this)));

[bryeung, 2013/01/08 22:24:27]

Remind me why using an Unretained here is safe...?

[youngki, 2013/01/09 15:12:03]

First of all my understanding is that AshSystemTrayDelegate is destroyed only
when the browser shuts down. That means that base::Unretained(this) is safe
unless it is a shutdown time. But during shutdown BluetoothAdapter will also be
destroyed and this callback won't be run then.

[bryeung, 2013/01/09 15:28:01]

And you're sure that:
- this is also true of the other places you've used this pattern?
- this doesn't introduce a race condition where shutdown has started and then
the callback is called

If so, then I agree it's okay.

[youngki, 2013/01/09 19:32:24]

I gave a second thought, and there might be race conditions if BluetoothAdapter
is destroyed later than the other modules during the shutdown. Also
BluetoothExtensionFunction is not live for the entire browser lifetime anyways.

So I changed the code to use weak pointer instead of base::Unretained(this).

+  }
+
+  bool InitializeOnAdapterReady(

[bryeung, 2013/01/08 22:24:27]

why does this need to return a value?

[youngki, 2013/01/09 15:12:03]

This is @asargent's suggestion to make BluetoothExtensionFunction::DoWork() to
return bool, not because the return data is meaningful, but so that we don't
have to manually put in the code to duplicate EXTENSION_FUNCTION_VALIDATE macro
in that function. EXTENSION_FUNCTION_VALIDATE returns false, and that requires
the signature of the function to return bool.

[bryeung, 2013/01/09 15:28:01]

Makes sense.  Okay.

[youngki, 2013/01/09 19:32:24]

I actually changed it to void because weak pointer does not allow to bind the
method that returns. Instead, I added a void RunOnAdapterCallback() which simply
calls DoWork() in BluetoothExtensionFunction and used that as a callback
instead.

+      scoped_refptr<device::BluetoothAdapter> adapter) {
+    bluetooth_adapter_ = adapter;
     bluetooth_adapter_->AddObserver(this);
 
     local_state_registrar_.Init(g_browser_process->local_state());
 
     UpdateSessionStartTime();
     UpdateSessionLengthLimit();
 
     local_state_registrar_.Add(
         prefs::kSessionStartTime,
         base::Bind(&SystemTrayDelegate::UpdateSessionStartTime,
                    base::Unretained(this)));
     local_state_registrar_.Add(
         prefs::kSessionLengthLimit,
         base::Bind(&SystemTrayDelegate::UpdateSessionLengthLimit,
                    base::Unretained(this)));
 
     policy::BrowserPolicyConnector* policy_connector =
         g_browser_process->browser_policy_connector();
     policy::DeviceCloudPolicyManagerChromeOS* policy_manager =
         policy_connector->GetDeviceCloudPolicyManager();
     if (policy_manager)
       policy_manager->core()->store()->AddObserver(this);
     UpdateEnterpriseDomain();
+
+    return true;
   }
 
   virtual ~SystemTrayDelegate() {
     AudioHandler* audiohandler = AudioHandler::GetInstance();
     if (audiohandler)
       audiohandler->RemoveVolumeObserver(this);
     DBusThreadManager::Get()->GetSessionManagerClient()->RemoveObserver(this);
     DBusThreadManager::Get()->GetRootPowerManagerClient()->RemoveObserver(this);
     DBusThreadManager::Get()->GetPowerManagerClient()->RemoveObserver(this);
     NetworkLibrary* crosnet = CrosLibrary::Get()->GetNetworkLibrary();
@@ skipping 1092 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(SystemTrayDelegate);
 };
 
 }  // namespace
 
 ash::SystemTrayDelegate* CreateSystemTrayDelegate() {
   return new chromeos::SystemTrayDelegate();
 }
 
 }  // namespace chromeos