Mass-migrate users of base::ThreadPool() as a trait to base::ThreadPool:: API [a-c]

Split directories [a* - components] (%chrome + fuchsia) from
https://chromium-review.googlesource.com/c/chromium/src/+/2026350
as it had trouble landing in one go.

The following script was used to generate this CL (run on every C++
file in the codebase; processing .h before matching .cc/.mm):
https://bugs.chromium.org/p/chromium/issues/detail?id=1026641#c22
(intentionally ignores cleaning post_task.h for now).

[email protected]

Bug: 1026641
Change-Id: I611ee5abce6daf14f80fbbf41e1fc14b6a1411d8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2075097
Reviewed-by: Gabriel Charette <[email protected]>
Reviewed-by: François Doray <[email protected]>
Commit-Queue: Gabriel Charette <[email protected]>
Cr-Commit-Position: refs/heads/master@{#744724}
diff --git a/components/update_client/update_client_unittest.cc b/components/update_client/update_client_unittest.cc
index 9361333..1dc0f1d 100644
--- a/components/update_client/update_client_unittest.cc
+++ b/components/update_client/update_client_unittest.cc
@@ -18,6 +18,7 @@
 #include "base/stl_util.h"
 #include "base/task/post_task.h"
 #include "base/task/task_traits.h"
+#include "base/task/thread_pool.h"
 #include "base/test/scoped_path_override.h"
 #include "base/test/task_environment.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ -1649,8 +1650,8 @@
 
       unpack_path_ = unpack_path;
       EXPECT_TRUE(base::DirectoryExists(unpack_path_));
-      base::PostTask(
-          FROM_HERE, {base::ThreadPool(), base::MayBlock()},
+      base::ThreadPool::PostTask(
+          FROM_HERE, {base::MayBlock()},
           base::BindOnce(std::move(callback),
                          CrxInstaller::Result(InstallError::GENERIC_ERROR)));
     }