Add HTTPBodyStream interface, three concrete implementations, and their tests.

util/util.gyp

 # Copyright 2014 The Crashpad Authors. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
 #     http://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 51 matching lines @@
         'misc/clock.h',
         'misc/clock_mac.cc',
         'misc/initialization_state.h',
         'misc/initialization_state_dcheck.cc',
         'misc/initialization_state_dcheck.h',
         'misc/scoped_forbid_return.cc',
         'misc/scoped_forbid_return.h',
         'misc/symbolic_constants_common.h',
         'misc/uuid.cc',
         'misc/uuid.h',
+        'net/http_body.cc',
+        'net/http_body.h',
         'numeric/checked_range.h',
         'numeric/in_range_cast.h',
         'numeric/int128.h',
         'numeric/safe_assignment.h',
         'posix/process_util.h',
         'posix/process_util_mac.cc',
         'posix/symbolic_constants_posix.cc',
         'posix/symbolic_constants_posix.h',
         'stdlib/cxx.h',
         'stdlib/objc.h',
@@ skipping 123 matching lines @@
         'mach/mach_extensions_test.cc',
         'mach/mach_message_server_test.cc',
         'mach/scoped_task_suspend_test.cc',
         'mach/symbolic_constants_mach_test.cc',
         'mach/task_memory_test.cc',
         'misc/clock_test.cc',
         'misc/initialization_state_dcheck_test.cc',
         'misc/initialization_state_test.cc',
         'misc/scoped_forbid_return_test.cc',
         'misc/uuid_test.cc',
+        'net/http_body_test.cc',
         'numeric/checked_range_test.cc',
         'numeric/in_range_cast_test.cc',
         'numeric/int128_test.cc',
         'posix/process_util_test.cc',
         'posix/symbolic_constants_posix_test.cc',
         'stdlib/string_number_conversion_test.cc',
         'stdlib/strlcpy_test.cc',
         'stdlib/strnlen_test.cc',
         'synchronization/semaphore_test.cc',
         'test/executable_path_test.cc',
@@ skipping 13 matching lines @@
     },
     {
       'target_name': 'util_test_multiprocess_exec_test_child',
       'type': 'executable',
       'sources': [
         'test/multiprocess_exec_test_child.cc',
       ],
     },
   ],
 }