remove unittests for fake cryptohoem client.

FakeCryptohomeClient doesn't have any exsiting test items after re
remove TpmAttestationSignSimpleChallenge.

BUG=b:158955123
TEST=build ok.

Change-Id: Ib533e261d1733f4449e2b3a783757279a35eefdb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2504011
Commit-Queue: Leo Lai <cylai@google.com>
Reviewed-by: Maksim Ivanov <emaxx@chromium.org>
Cr-Commit-Position: refs/heads/master@{#823180}

chromeos/dbus/BUILD.gn

@@ -214,7 +214,6 @@ source_set("unit_tests") {
     "blocking_method_caller_unittest.cc",
     "cec_service_client_unittest.cc",
     "cros_disks_client_unittest.cc",
-    "cryptohome/fake_cryptohome_client_unittest.cc",
     "dbus_thread_manager_unittest.cc",
     "fake_easy_unlock_client_unittest.cc",
     "fake_gnubby_client_unittest.cc",

chromeos/dbus/cryptohome/fake_cryptohome_client_unittest.cc

-// Copyright 2016 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 "chromeos/dbus/cryptohome/fake_cryptohome_client.h"
-
-#include <string>
-
-#include "base/bind.h"
-#include "base/bind_helpers.h"
-#include "base/run_loop.h"
-#include "base/scoped_observer.h"
-#include "base/test/task_environment.h"
-#include "chromeos/dbus/attestation/attestation.pb.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-namespace chromeos {
-
-namespace {
-
-// Keeps arguments for the last AsyncCallStatusWithData().
-class TestObserver : public CryptohomeClient::Observer {
- public:
-  TestObserver() = default;
-
-  bool return_status() const { return return_status_; }
-  const std::string& data() const { return data_; }
-
-  void AsyncCallStatusWithData(int async_id,
-                               bool return_status,
-                               const std::string& data) override {
-    return_status_ = return_status;
-    data_ = data;
-  }
-
- private:
-  bool return_status_ = false;
-  std::string data_;
-  DISALLOW_COPY_AND_ASSIGN(TestObserver);
-};
-
-}  // namespace
-
-class FakeCryptohomeClientTest : public ::testing::Test {
- public:
-  FakeCryptohomeClientTest() = default;
-
- protected:
-  base::test::TaskEnvironment task_environment_;
-  FakeCryptohomeClient fake_cryptohome_client_;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(FakeCryptohomeClientTest);
-};
-
-}  // namespace chromeos