DCHECK..ON(BrowserThread::UI) -> DCHECK(thread_checker_.CalledOnValidThread())

This changelist removes one unnecessary dependency from
chrome/browser/chromeos/drive
to
content/public/browser/browser_thread.h

- Where possible
      DCHECK_CURRENTLY_ON(BrowserThread::UI)
  is replaced with
      DCHECK(thread_checker_.CalledOnValidThread())

- The new DCHECK is in theory more relaxed than the original DCHECK, but
  in practice is no different, assumming that objects (and therefore the
  newly added base::ThreadChecker field) are created from the UI thread
  (in practice this is enforced by DCHECK_CURRENTLY_ON(BrowserThread::UI)
  in the constructor and methods of DriveIntegrationService).

- The old DCHECK is left untouched in places that do not have to be
  reused outside of a browser (most notably - browser-specific
  file_system_util.cc and most of drive_integration_service.cc).

- The old DCHECK is removed without adding the new DCHECK in a few
  places where base::ThreadChecker could not be used in a straightforward
  way (i.e. in standalone functions or callbacks).

BUG=498951
TEST=built (GYP_DEFINES="... chromeos=1") and run unit_tests gyp/ninja target from chrome/chrome_tests_unit.gypi

Review URL: https://codereview.chromium.org/1177823002

Cr-Commit-Position: refs/heads/master@{#334127}

1 files changed, 3 insertions, 0 deletions

diff --git a/chrome/browser/chromeos/drive/file_write_watcher.h b/chrome/browser/chromeos/drive/file_write_watcher.h
index 63ee9f5..68004ca 100644
--- a/chrome/browser/chromeos/drive/file_write_watcher.h
+++ b/chrome/browser/chromeos/drive/file_write_watcher.h
@@ -7,6 +7,7 @@
 
 #include "base/callback_forward.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/threading/thread_checker.h"
 #include "chrome/browser/chromeos/drive/file_system_util.h"
 
 namespace base {
@@ -54,6 +55,8 @@ class FileWriteWatcher {
   class FileWriteWatcherImpl;
   scoped_ptr<FileWriteWatcherImpl, util::DestroyHelper> watcher_impl_;
 
+  base::ThreadChecker thread_checker_;
+
   DISALLOW_COPY_AND_ASSIGN(FileWriteWatcher);
 };