With this CL, there is no remaining call to these methods on Mac:
- MessageLoop::PostTask
- MessageLoop::PostDelayedTask
- MessageLoop::ReleaseSoon
- MessageLoop::DeleteSoon
- MessageLoop::Run
- MessageLoop::RunUntilIdle

Note that this CL also removes calls to these methods from files that
are not built on Mac.

These calls were not migrated by the clang-tidy script used previously
for various reasons (Objective-C code, templates, macros, header files,
std::unique_ptr<MessageLoop>...).

This CL was generated manually (with the help of a few regular
expressions).

BUG=616447
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_optional_gpu_tests_rel;tryserver.chromium.mac:mac_optional_gpu_tests_rel;tryserver.chromium.win:win_optional_gpu_tests_rel
TBR=sdefresne@chromium.org (for ios/'s trivial application of this refactoring)

Review-Url: https://codereview.chromium.org/2132593002
Cr-Commit-Position: refs/heads/master@{#406148}