FilePathWatcher::Watch() - Listen for sub directory changes.

base/files/file_path_watcher_kqueue.cc

Index: base/files/file_path_watcher_kqueue.cc
diff --git a/base/files/file_path_watcher_kqueue.cc b/base/files/file_path_watcher_kqueue.cc
index 6221a62f379e2385dadabca22de0893451c92068..251a172815f8ef49eaf8585c5d7342e8dbd8adea 100644
--- a/base/files/file_path_watcher_kqueue.cc
+++ b/base/files/file_path_watcher_kqueue.cc
@@ -12,6 +12,7 @@
 
 #include "base/bind.h"
 #include "base/file_util.h"
+#include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/message_loop_proxy.h"
 #include "base/stringprintf.h"
@@ -64,6 +65,7 @@ class FilePathWatcherImpl : public FilePathWatcher::PlatformDelegate,
 
   // FilePathWatcher::PlatformDelegate overrides.
   virtual bool Watch(const FilePath& path,
+                     bool recursive,
                      FilePathWatcher::Delegate* delegate) OVERRIDE;
   virtual void Cancel() OVERRIDE;
 
@@ -428,12 +430,18 @@ void FilePathWatcherImpl::WillDestroyCurrentMessageLoop() {
 }
 
 bool FilePathWatcherImpl::Watch(const FilePath& path,
+                                bool recursive,
                                 FilePathWatcher::Delegate* delegate) {
   DCHECK(MessageLoopForIO::current());
   DCHECK(target_.value().empty());  // Can only watch one path.
   DCHECK(delegate);
   DCHECK_EQ(kqueue_, -1);
 
+  if (recursive) {
+    NOTIMPLEMENTED();

[Mattias Nissler (ping if slow), 2012/11/21 09:28:48]

What's the effect of this at run time? I'd rather have something that CHECKS()
or at least DCHECKS() to avoid surprises.

[Lei Zhang, 2012/11/21 20:01:09]

I don't think we want to put in CHECKs. Let's say we are on "foo OS" and foo OS
does not provide any way to do recursive watches. If we had a CHECK here, the
higher level code that wants to call FilePathWatcher would need to know they
cannot do so on foo OS. That makes FilePathWatcher harder to use.

As is, calls to FilePathWatcher on foo OS would just return false, and the
caller can handle the false case, which it should be doing anyway.

file_path_watcher.h should have clear documentation that the recursive flag may
fail on platforms, so callers know what to expect.

[Mattias Nissler (ping if slow), 2012/11/22 08:51:34]

All right, you convinced me that returning false is probably good enough.

+    return false;
+  }
+
   delegate_ = delegate;
   target_ = path;