Use FileDescriptorWatcher in ProcessOutputWatcher

chromeos/process_proxy/process_output_watcher.h

Index: chromeos/process_proxy/process_output_watcher.h
diff --git a/chromeos/process_proxy/process_output_watcher.h b/chromeos/process_proxy/process_output_watcher.h
index 168c586a82dc0ce7e86ca02557bf1c1ee9a9ffc0..3b7f489aa2ebf1bbc5793416caf811a93bd59898 100644
--- a/chromeos/process_proxy/process_output_watcher.h
+++ b/chromeos/process_proxy/process_output_watcher.h
@@ -7,13 +7,14 @@
 
 #include <stddef.h>
 
+#include <memory>
 #include <string>
 
 #include "base/callback.h"
 #include "base/files/file.h"
+#include "base/files/file_descriptor_watcher_posix.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
-#include "base/message_loop/message_loop.h"
 #include "chromeos/chromeos_export.h"
 
 namespace chromeos {
@@ -29,18 +30,16 @@ typedef base::Callback<void(ProcessOutputType,
 
 // Observes output on |out_fd| and invokes |callback| when some output is
 // detected. It assumes UTF8 output.
-class CHROMEOS_EXPORT ProcessOutputWatcher
-    : public base::MessageLoopForIO::Watcher {
+class CHROMEOS_EXPORT ProcessOutputWatcher {
  public:
   ProcessOutputWatcher(int out_fd, const ProcessOutputCallback& callback);
-  ~ProcessOutputWatcher() override;
+  ~ProcessOutputWatcher();
 
   void Start();
 
  private:
-  // MessageLoopForIO::Watcher overrides:
-  void OnFileCanReadWithoutBlocking(int fd) override;
-  void OnFileCanWriteWithoutBlocking(int fd) override;
+  // Called when |process_output_file_| is readable without blocking.
+  void OnProcessOutputCanReadWithoutBlocking();
 
   // Listens to output from fd passed to the constructor.
   void WatchProcessOutput();
@@ -66,7 +65,7 @@ class CHROMEOS_EXPORT ProcessOutputWatcher
 
   // Contains file descsriptor to which watched process output is written.
   base::File process_output_file_;
-  base::MessageLoopForIO::FileDescriptorWatcher output_file_watcher_;
+  std::unique_ptr<base::FileDescriptorWatcher::Controller> output_file_watcher_;
 
   // Callback that will be invoked when some output is detected.
   ProcessOutputCallback on_read_callback_;