kqueue implementation of FilePathWatcher on Mac.

content/common/file_path_watcher/file_path_watcher.h

Index: content/common/file_path_watcher/file_path_watcher.h
diff --git a/content/common/file_path_watcher/file_path_watcher.h b/content/common/file_path_watcher/file_path_watcher.h
index 2ec7af5ac5e1cb97825bb7f6f6a6c9213f0cf951..20ccfcc447b0854c69b6c2553574870ca27e214b 100644
--- a/content/common/file_path_watcher/file_path_watcher.h
+++ b/content/common/file_path_watcher/file_path_watcher.h
@@ -16,8 +16,12 @@
 // This class lets you register interest in changes on a FilePath.
 // The delegate will get called whenever the file or directory referenced by the
 // FilePath is changed, including created or deleted. Due to limitations in the
-// underlying OS APIs, spurious notifications might occur that don't relate to
-// an actual change to the watch target.
+// underlying OS APIs, FilePathWatcher has slightly different semantics on OS X
+// than on Windows or Linux. FilePathWatcher on Linux and Windows will detect
+// modifications to files in a watched directory. FilePathWatcher on Mac will
+// detect the creation and deletion of files in a watched directory, but will
+// not detect modifications to those files. See file_path_watcher_mac.cc for
+// details.
 class FilePathWatcher {
  public:
   // Declares the callback client code implements to receive notifications. Note
@@ -36,15 +40,10 @@ class FilePathWatcher {
   ~FilePathWatcher();
 
   // Register interest in any changes on |path|. OnPathChanged will be called
-  // back for each change. Returns true on success. |loop| is only used
-  // by the Mac implementation right now, and must be backed by a CFRunLoop
-  // based MessagePump. This is usually going to be a MessageLoop of type
-  // TYPE_UI.
+  // back for each change. Returns true on success.
   // OnFilePathChanged() will be called on the same thread as Watch() is called,
   // which should have a MessageLoop of TYPE_IO.
-  bool Watch(const FilePath& path,
-             Delegate* delegate,
-             base::MessageLoopProxy* loop) WARN_UNUSED_RESULT;
+  bool Watch(const FilePath& path, Delegate* delegate) WARN_UNUSED_RESULT;
 
   class PlatformDelegate;
 
@@ -73,13 +72,8 @@ class FilePathWatcher {
     PlatformDelegate();
 
     // Start watching for the given |path| and notify |delegate| about changes.
-    // |loop| is only used by the Mac implementation right now, and must be
-    // backed by a CFRunLoop based MessagePump. This is usually going to be a
-    // MessageLoop of type TYPE_UI.
-    virtual bool Watch(
-        const FilePath& path,
-        Delegate* delegate,
-        base::MessageLoopProxy* loop) WARN_UNUSED_RESULT = 0;
+    virtual bool Watch(const FilePath& path,
+                       Delegate* delegate) WARN_UNUSED_RESULT = 0;
 
     // Stop watching. This is called from FilePathWatcher's dtor in order to
     // allow to shut down properly while the object is still alive.