Migrate HidServiceLinux and HidConnectionLinux to BrowserThread::UI.

This patch is a follow-up to https://crrev.com/e8fa00efd0965a7eb5816a
that moves the HidService and HidConnection implementations on Linux
from the browser's FILE thread to the UI thread. This is being done
because the HID APIs on platforms other than Linux are more natural to
use on the UI thread. The users of these objects are also usually on
the UI thread. (For example, the extension API bindings.)

BUG=422540

Review URL: https://codereview.chromium.org/771393002

Cr-Commit-Position: refs/heads/master@{#306729}

1 files changed, 3 insertions, 6 deletions

diff --git a/device/hid/hid_service.cc b/device/hid/hid_service.cc
index 071b396..78273ae6 100644
--- a/device/hid/hid_service.cc
+++ b/device/hid/hid_service.cc
@@ -4,9 +4,7 @@
 
 #include "device/hid/hid_service.h"
 
-#include "base/lazy_instance.h"
 #include "base/logging.h"
-#include "base/memory/scoped_vector.h"
 #include "base/message_loop/message_loop.h"
 #include "base/stl_util.h"
 
@@ -45,11 +43,10 @@ class HidService::Destroyer : public base::MessageLoop::DestructionObserver {
 };
 
 HidService* HidService::GetInstance(
-    scoped_refptr<base::SingleThreadTaskRunner> file_task_runner,
-    scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner) {
+    scoped_refptr<base::SingleThreadTaskRunner> file_task_runner) {
   if (g_service == NULL) {
 #if defined(OS_LINUX) && defined(USE_UDEV)
-    g_service = new HidServiceLinux(ui_task_runner);
+    g_service = new HidServiceLinux(file_task_runner);
 #elif defined(OS_MACOSX)
     g_service = new HidServiceMac(file_task_runner);
 #elif defined(OS_WIN)
@@ -87,6 +84,7 @@ void HidService::GetDevices(std::vector<HidDeviceInfo>* devices) {
 // Fills in the device info struct of the given device_id.
 bool HidService::GetDeviceInfo(const HidDeviceId& device_id,
                                HidDeviceInfo* info) const {
+  DCHECK(thread_checker_.CalledOnValidThread());
   DeviceMap::const_iterator it = devices_.find(device_id);
   if (it == devices_.end())
     return false;
@@ -95,7 +93,6 @@ bool HidService::GetDeviceInfo(const HidDeviceId& device_id,
 }
 
 HidService::HidService() {
-  DCHECK(thread_checker_.CalledOnValidThread());
 }
 
 void HidService::AddDevice(const HidDeviceInfo& info) {