cryptohome: Do not ignore the system slot id returned by GetTpmTokenSlotForPath

When TPM/chaps is not fully initialized, the method returns -1 and Chrome should
attempt a retry later. The existing implementation overwrote the slot id always
by 0 and as a result disabled the retry, leading to a failure on establishing
the device ownership on certain cases.

BUG=b/37259691
TEST=`cros flash ssh://dut xbuddy://remote/samus/R61-9693.0.0/test;
 test_that --args="value='samus-release/R61-9694.0.0'" provision_AutoUpdate;
 test_that cheets_StartAndroid` > "Manage other people" setting is modifiable.

Change-Id: I9ebb731ba8004a61a9d868f3e586fe32d1979ab9
Reviewed-on: https://chromium-review.googlesource.com/558528Reviewed-by: Matt Mueller <mattm@chromium.org>
Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
Commit-Queue: Kazuhiro Inaba <kinaba@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487409}

chromeos/dbus/cryptohome_client.cc

@@ -399,11 +399,9 @@ class CryptohomeClientImpl : public CryptohomeClient {
     dbus::MessageWriter writer(&method_call);
     writer.AppendString(cryptohome_id.id());
     proxy_->CallMethod(
-        &method_call, kTpmDBusTimeoutMs ,
-        base::Bind(
-            &CryptohomeClientImpl::OnPkcs11GetTpmTokenInfoForUser,
-            weak_ptr_factory_.GetWeakPtr(),
-            callback));
+        &method_call, kTpmDBusTimeoutMs,
+        base::Bind(&CryptohomeClientImpl::OnPkcs11GetTpmTokenInfo,
+                   weak_ptr_factory_.GetWeakPtr(), callback));
   }
 
   // CryptohomeClient override.
@@ -1136,7 +1134,8 @@ class CryptohomeClientImpl : public CryptohomeClient {
     callback.Run(DBUS_METHOD_CALL_SUCCESS, true, reply);
   }
 
-  // Handles responses for Pkcs11GetTpmTokenInfo.
+  // Handles responses for Pkcs11GetTpmTokenInfo and
+  // Pkcs11GetTpmTokenInfoForUser.
   void OnPkcs11GetTpmTokenInfo(const Pkcs11GetTpmTokenInfoCallback& callback,
                                dbus::Response* response) {
     if (!response) {
@@ -1146,26 +1145,6 @@ class CryptohomeClientImpl : public CryptohomeClient {
     dbus::MessageReader reader(response);
     std::string label;
     std::string user_pin;
-    if (!reader.PopString(&label) || !reader.PopString(&user_pin)) {
-      callback.Run(DBUS_METHOD_CALL_FAILURE, std::string(), std::string(), -1);
-      LOG(ERROR) << "Invalid response: " << response->ToString();
-      return;
-    }
-    const int kDefaultSlot = 0;
-    callback.Run(DBUS_METHOD_CALL_SUCCESS, label, user_pin, kDefaultSlot);
-  }
-
-  // Handles responses for Pkcs11GetTpmTokenInfoForUser.
-  void OnPkcs11GetTpmTokenInfoForUser(
-      const Pkcs11GetTpmTokenInfoCallback& callback,
-      dbus::Response* response) {
-    if (!response) {
-      callback.Run(DBUS_METHOD_CALL_FAILURE, std::string(), std::string(), -1);
-      return;
-    }
-    dbus::MessageReader reader(response);
-    std::string label;
-    std::string user_pin;
     int slot = 0;
     if (!reader.PopString(&label) || !reader.PopString(&user_pin) ||
         !reader.PopInt32(&slot)) {