Migrate HidServiceLinux and HidConnectionLinux to BrowserThread::UI.

device/hid/hid_connection_linux.h

Index: device/hid/hid_connection_linux.h
diff --git a/device/hid/hid_connection_linux.h b/device/hid/hid_connection_linux.h
index 4850d6a04edd06838928f369b7c59f6f3cba0a9c..d6befe44e3b20e4ffd83952d44d5447e6eaf9b78 100644
--- a/device/hid/hid_connection_linux.h
+++ b/device/hid/hid_connection_linux.h
@@ -8,18 +8,30 @@
 #include <queue>
 
 #include "base/files/file.h"
-#include "base/message_loop/message_pump_libevent.h"
+#include "base/memory/weak_ptr.h"
 #include "device/hid/hid_connection.h"
 
+namespace base {
+class SingleThreadTaskRunner;
+}
+
 namespace device {
 
-class HidConnectionLinux : public HidConnection,
-                           public base::MessagePumpLibevent::Watcher {
+class HidConnectionLinux : public HidConnection {
  public:
-  HidConnectionLinux(HidDeviceInfo device_info, std::string dev_node);
+  HidConnectionLinux(
+      HidDeviceInfo device_info,
+      base::File device_file,
+      scoped_refptr<base::SingleThreadTaskRunner> file_thread_runner);
 
  private:
+  class Helper;
+  friend class Helper;
   friend class base::RefCountedThreadSafe<HidConnectionLinux>;
+
+  typedef base::Callback<void(ssize_t)> InternalWriteCallback;
+  typedef base::Callback<void(int)> IoctlCallback;
+
   ~HidConnectionLinux() override;
 
   // HidConnection implementation.
@@ -34,22 +46,52 @@ class HidConnectionLinux : public HidConnection,
                                  size_t size,
                                  const WriteCallback& callback) override;
 
-  // base::MessagePumpLibevent::Watcher implementation.
-  void OnFileCanReadWithoutBlocking(int fd) override;
-  void OnFileCanWriteWithoutBlocking(int fd) override;
+  // Callbacks for blocking operations run on the FILE thread.
+  void FinishWrite(size_t expected_size,
+                   const WriteCallback& callback,
+                   ssize_t result);
+  void FinishGetFeatureReport(uint8_t report_id,
+                              scoped_refptr<net::IOBuffer> buffer,
+                              const ReadCallback& callback,
+                              int result);
+  void FinishSendFeatureReport(const WriteCallback& callback, int result);
+
+  // Starts the FileDescriptorWatcher that reads input events from the device.
+  // Must be called on a thread that has a base::MessageLoopForIO.
+  void StartHelper(base::WeakPtr<HidConnectionLinux> weak_ptr);
 
-  void Disconnect();
+  // Writes to the device. This operation may block.
+  static void BlockingWrite(
+      base::PlatformFile platform_file,
+      scoped_refptr<net::IOBuffer> buffer,
+      size_t size,
+      const InternalWriteCallback& callback,
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner);
+  // Performs an ioctl on the device. This operation may block.
+  static void BlockingIoctl(
+      base::PlatformFile platform_file,
+      int request,
+      scoped_refptr<net::IOBuffer> buffer,
+      const IoctlCallback& callback,
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner);
+
+  // Closes the device file descriptor. Must be called on the FILE thread.
+  static void CloseDevice(base::File device_file);
 
-  void Flush();
   void ProcessInputReport(scoped_refptr<net::IOBuffer> buffer, size_t size);
   void ProcessReadQueue();
 
   base::File device_file_;
-  base::MessagePumpLibevent::FileDescriptorWatcher device_file_watcher_;
+  scoped_ptr<Helper> helper_;
+
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+  scoped_refptr<base::SingleThreadTaskRunner> file_task_runner_;
 
   std::queue<PendingHidReport> pending_reports_;
   std::queue<PendingHidRead> pending_reads_;
 
+  base::WeakPtrFactory<HidConnectionLinux> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(HidConnectionLinux);
 };