Remove MessageLoop destruction observer from hid_connection_linux.cc

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 bcdb99c1cc7d231b07e2346ce983b1aa4a27dc67..574c732638b810dcb96363749fab8bce70c64141 100644
--- a/device/hid/hid_connection_linux.h
+++ b/device/hid/hid_connection_linux.h
@@ -10,13 +10,14 @@
 
 #include <queue>
 
-#include "base/files/file.h"
+#include "base/files/scoped_file.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "base/sequence_checker.h"
 #include "device/hid/hid_connection.h"
 
 namespace base {
-class SingleThreadTaskRunner;
+class SequencedTaskRunner;
 }
 
 namespace device {
@@ -25,16 +26,13 @@ class HidConnectionLinux : public HidConnection {
  public:
   HidConnectionLinux(
       scoped_refptr<HidDeviceInfo> device_info,
-      base::File device_file,
-      scoped_refptr<base::SingleThreadTaskRunner> file_thread_runner);
+      base::ScopedFD fd,
+      scoped_refptr<base::SequencedTaskRunner> blocking_task_runner);
 
  private:
   friend class base::RefCountedThreadSafe<HidConnectionLinux>;
   class FileThreadHelper;
 
-  typedef base::Callback<void(ssize_t)> InternalWriteCallback;
-  typedef base::Callback<void(int)> IoctlCallback;
-
   ~HidConnectionLinux() override;
 
   // HidConnection implementation.
@@ -49,46 +47,21 @@ class HidConnectionLinux : public HidConnection {
                                  size_t size,
                                  const WriteCallback& callback) 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);
-
-  // 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 ProcessInputReport(scoped_refptr<net::IOBuffer> buffer, size_t size);
   void ProcessReadQueue();
 
-  base::File device_file_;
-  FileThreadHelper* helper_;
+  // This object lives on the sequence to which |blocking_task_runner_| posts
+  // tasks so all calls must be posted there including this object's
+  // destruction.
+  std::unique_ptr<FileThreadHelper> helper_;
 
-  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
-  scoped_refptr<base::SingleThreadTaskRunner> file_task_runner_;
+  const scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
 
   std::queue<PendingHidReport> pending_reports_;
   std::queue<PendingHidRead> pending_reads_;
 
+  base::SequenceChecker sequence_checker_;
+
   base::WeakPtrFactory<HidConnectionLinux> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(HidConnectionLinux);