cros: Replace BrowserThread::FILE in InputServiceProxy

chrome/browser/chromeos/device/input_service_proxy.h

Index: chrome/browser/chromeos/device/input_service_proxy.h
diff --git a/chrome/browser/chromeos/device/input_service_proxy.h b/chrome/browser/chromeos/device/input_service_proxy.h
index 3c00da6e381eebf32ed42eabca038795c4c45f47..c78c62359ebb4846279f912f403e726060fda3fa 100644
--- a/chrome/browser/chromeos/device/input_service_proxy.h
+++ b/chrome/browser/chromeos/device/input_service_proxy.h
@@ -14,7 +14,6 @@
 #include "base/observer_list.h"
 #include "base/task_runner.h"
 #include "base/threading/thread_checker.h"
-#include "content/public/browser/browser_thread.h"
 #include "device/hid/input_service_linux.h"
 
 namespace chromeos {
@@ -48,11 +47,11 @@ class InputServiceProxy {
                      const GetDeviceInfoCallback& callback);
 
   // Should be called once before any InputServiceProxy instance is created.

[achuithb, 2017/06/15 23:04:59]

Should we move this comment after the using declaration?

[xiyuan, 2017/06/16 19:21:27]

will do

-  static void SetThreadIdForTesting(content::BrowserThread::ID thread_id);
+  using TaskRunnerFactory =
+      base::Callback<scoped_refptr<base::TaskRunner>(void)>;

[achuithb, 2017/06/15 23:04:59]

I'm curious if this is the standard pattern now for switching between UI and
background threads? It's a bit tricky with pointers to callbacks that bind
lambda's.

[xiyuan, 2017/06/16 19:21:27]

Not a standard pattern. I used this because it fits in with the current test
code. I could also make it a boolean though since there are only two tests use
this and both want UI thread.

+  static void SetTaskRunnerFactoryForTesting(TaskRunnerFactory* factory);
 
  private:
-  static content::BrowserThread::ID thread_identifier_;
-
   class ServiceObserver;
 
   void OnDeviceAdded(const device::InputServiceLinux::InputDeviceInfo& info);