Remove Mojo bindings environment.

mojo/public/cpp/environment/lib/default_task_tracker.cc

-// Copyright 2015 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 "mojo/public/cpp/environment/lib/default_task_tracker.h"
-
-#include "mojo/public/cpp/environment/task_tracker.h"
-
-namespace mojo {
-
-namespace {
-
-//
-// The standalone task tracker does nothing.
-//
-
-TaskTrackingId StartTracking(const char* function_name,
-                             const char* file_name,
-                             int line_number,
-                             const void* program_counter) {
-  return TaskTrackingId(0);
-}
-
-void EndTracking(const TaskTrackingId id) {
-}
-
-void SetEnabled(bool enabled) {
-}
-
-}  // namespace
-
-namespace internal {
-
-const TaskTracker kDefaultTaskTracker = {&StartTracking,
-                                         &EndTracking,
-                                         &SetEnabled};
-
-}  // namespace internal
-
-}  // namespace mojo