Convert chromeos::CryptohomeClient::TpmCanAttemptOwnership to asynchronous

chromeos/dbus/cryptohome_client.h

Index: chromeos/dbus/cryptohome_client.h
diff --git a/chromeos/dbus/cryptohome_client.h b/chromeos/dbus/cryptohome_client.h
index 2d619dab151279de99ed9f230eb88200eee5e8dc..c79e206686f55169859c40bf157f14cc5404ca56 100644
--- a/chromeos/dbus/cryptohome_client.h
+++ b/chromeos/dbus/cryptohome_client.h
@@ -30,6 +30,9 @@ class CHROMEOS_EXPORT CryptohomeClient {
                          > AsyncCallStatusHandler;
   // A callback to handle responses of AsyncXXX methods.
   typedef base::Callback<void(int async_id)> AsyncMethodCallback;
+  // A callback to handle responses of methods without result values.
+  typedef base::Callback<void(
+      DBusMethodCallStatus call_status)> VoidMethodCallback;

[stevenjb, 2012/07/26 17:19:52]

This and the two callbacks below seem generic enough to be defined with
DBusMethodCallStatus?

[hashimoto, 2012/07/27 04:37:18]

Sounds good, will do in a separate patch.

   // A callback to handle responses of methods returning a bool value.
   typedef base::Callback<void(DBusMethodCallStatus call_status,
                               bool result)> BoolMethodCallback;
@@ -122,9 +125,8 @@ class CHROMEOS_EXPORT CryptohomeClient {
   // This method blocks until the call returns.
   virtual bool TpmIsBeingOwned(bool* owning) = 0;
 
-  // Calls TpmCanAttemptOwnership method and returns true when the call
-  // succeeds.  This method blocks until the call returns.
-  virtual bool TpmCanAttemptOwnership() = 0;
+  // Calls TpmCanAttemptOwnership method.
+  virtual void TpmCanAttemptOwnership(const VoidMethodCallback& callback) = 0;

[stevenjb, 2012/07/26 17:19:52]

I'm confused about what this method does. It looks like it should return whether
or not we can attempt ownership, but in that case shouldn't the callback pass a
bool? Or does it tell cryptohome that it is OK to attempt ownership, in which
case we should rename this to something like SetTpmCanAttemptOwnership.

[hashimoto, 2012/07/27 04:37:18]

Looks like your latter guess is correct.
(http://git.chromium.org/gitweb/?p=chromiumos/platform/cryptohome.git;a=blob;f...)
This method is named badly from the beginning, I think it should be renamed to
something like MyabeStartInitializeTpm().
Anyway, I'm using the name "TpmCanAttemptOwnership" because the Cryptohome
service is providing the method with this name.
If we are going to rename this method, we should also rename Cryptohome
service's method name too.

[stevenjb, 2012/07/30 22:24:38]

OK, I see. That is definitely badly named. Can you at least comment what it does
and/or include the link?

[hashimoto, 2012/07/31 02:27:34]

Added a comment.

 
   // Calls TpmClearStoredPassword method and returns true when the call
   // succeeds.  This method blocks until the call returns.