[Ozone-Dri] Decouple the IO helper thread from DriWrapper

ui/ozone/platform/dri/dri_wrapper.cc

Index: ui/ozone/platform/dri/dri_wrapper.cc
diff --git a/ui/ozone/platform/dri/dri_wrapper.cc b/ui/ozone/platform/dri/dri_wrapper.cc
index 929dd27d8a45fd88f38269c6d35a38dac9530113..14939ac527217593264d1daeff3572b16d6a4af5 100644
--- a/ui/ozone/platform/dri/dri_wrapper.cc
+++ b/ui/ozone/platform/dri/dri_wrapper.cc
@@ -19,6 +19,7 @@
 #include "third_party/skia/include/core/SkImageInfo.h"
 #include "ui/ozone/platform/dri/dri_util.h"
 #include "ui/ozone/platform/dri/hardware_display_plane_manager_legacy.h"
+#include "ui/ozone/platform/dri/io_helper_thread.h"
 
 namespace ui {
 
@@ -144,11 +145,8 @@ class DriWrapper::IOWatcher
   DISALLOW_COPY_AND_ASSIGN(IOWatcher);
 };
 
-DriWrapper::DriWrapper(const char* device_path, bool use_sync_flips)
-    : fd_(-1),
-      use_sync_flips_(use_sync_flips),
-      device_path_(device_path),
-      io_thread_("DriIOThread") {
+DriWrapper::DriWrapper(const char* device_path, IOHelperThread* io_thread)
+    : fd_(-1), device_path_(device_path), io_thread_(io_thread) {
   plane_manager_.reset(new HardwareDisplayPlaneManagerLegacy());
 }
 
@@ -169,13 +167,11 @@ void DriWrapper::Initialize() {
 }
 
 void DriWrapper::InitializeIOWatcher() {
-  if (!use_sync_flips_ && !watcher_) {
-    if (!io_thread_.StartWithOptions(
-            base::Thread::Options(base::MessageLoop::TYPE_IO, 0)))
-      LOG(FATAL) << "Failed to start the IO helper thread";
+  if (!io_thread_->IsRunning())

[alexst (slow to review), 2015/01/22 15:27:48]

We should do this in
https://code.google.com/p/chromium/codesearch#chromium/src/ui/ozone/platform/...

It'll happen just before any ipc's start flowing.

[dnicoara, 2015/01/22 22:50:14]

Done.

+    io_thread_->Initialize();
 
-    watcher_ = new IOWatcher(fd_, io_thread_.task_runner());
-  }
+  if (!watcher_)
+    watcher_ = new IOWatcher(fd_, io_thread_->task_runner());
 }
 
 ScopedDrmCrtcPtr DriWrapper::GetCrtc(uint32_t crtc_id) {
@@ -278,7 +274,7 @@ bool DriWrapper::PageFlip(uint32_t crtc_id,
                        payload.get())) {
     // If successful the payload will be removed by a PageFlip event.
     ignore_result(payload.release());
-    if (use_sync_flips_) {
+    if (!io_thread_) {
       TRACE_EVENT1("dri", "OnDrmEvent", "socket", fd_);
 
       drmEventContext event;