base: remove ScopedBlockingCall from inotify_reader thread.

The inotify_reader thread is a dedicated thread and ScopedBlockingCall
is not needed here. It's polluting slow reports.

Bug=CHROMIUM:1057202

Change-Id: I42cadcc9b1f7553252e5643c3af080fdd7d53b77
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2078981
Auto-Submit: Brian Geffon <bgeffon@chromium.org>
Reviewed-by: Gabriel Charette <gab@chromium.org>
Commit-Queue: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745678}

base/files/file_path_watcher_linux.cc

@@ -271,9 +271,6 @@ void InotifyReaderThreadDelegate::ThreadMain() {
     FD_ZERO(&rfds);
     FD_SET(inotify_fd_, &rfds);
 
-    ScopedBlockingCall scoped_blocking_call(FROM_HERE,
-                                            BlockingType::WILL_BLOCK);
-
     // Wait until some inotify events are available.
     int select_result =
         HANDLE_EINTR(select(inotify_fd_ + 1, &rfds, nullptr, nullptr, nullptr));