task posting v3: moving away from ThreadTaskRunnerHandle

To continue the migration away from TaskRunnerHandles, the codebase
was refactored using the following scripts:
shell script:
https://paste.googleplex.com/4673967729147904
python:
https://paste.googleplex.com/5824001174667264

This will do a few sed-like modifications, changing calls to methods of
ThreadTaskRunnerHandle to calls to methods of
SingleThreadTaskRunner::CurrentDefaultHandle, and swapping includes.

Bug: 1026641
AX-Relnotes: n/a.
Change-Id: Ia33b6dfebb15937481c619f5c838720ce7bb2676
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4031817
Commit-Queue: Gabriel Charette <gab@chromium.org>
Reviewed-by: Gabriel Charette <gab@chromium.org>
Owners-Override: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1074085}

diff --git a/ipc/ipc_channel_proxy_unittest.cc b/ipc/ipc_channel_proxy_unittest.cc
index c3af197..0a9ccfb 100644
--- a/ipc/ipc_channel_proxy_unittest.cc
+++ b/ipc/ipc_channel_proxy_unittest.cc

@@ -251,7 +251,8 @@
     listener_ = std::make_unique<QuitListener>();
     channel_proxy_ = IPC::ChannelProxy::Create(
         TakeHandle().release(), IPC::Channel::MODE_SERVER, listener_.get(),
-        thread_->task_runner(), base::ThreadTaskRunnerHandle::Get());
+        thread_->task_runner(),
+        base::SingleThreadTaskRunner::GetCurrentDefault());
   }
 
   void TearDown() override {