Enable file path watcher for Android

base/files/file_path_watcher_linux.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/files/file_path_watcher.h"
 
 #include <errno.h>
 #include <string.h>
 #include <sys/inotify.h>
 #include <sys/ioctl.h>
@@ skipping 355 matching lines @@
   DCHECK(MessageLoopForIO::current());
 
   set_message_loop(base::MessageLoopProxy::current());
   delegate_ = delegate;
   target_ = path;
   MessageLoop::current()->AddDestructionObserver(this);
 
   std::vector<FilePath::StringType> comps;
   target_.GetComponents(&comps);
   DCHECK(!comps.empty());
-  for (std::vector<FilePath::StringType>::const_iterator comp(++comps.begin());

[jar (doing other things), 2012/08/30 02:47:25]

I didn't especially like this pre-increment on the return from begin(), but it
wasn't clear why the new code was different.

Can you point out the change here?  ...was it just to make a compiler happy??

[yongsheng, 2012/08/30 04:50:17]

yes, see the compiler error on Android.

-       comp != comps.end(); ++comp) {
+  std::vector<FilePath::StringType>::const_iterator comp = comps.begin();

[Mark Mentovai, 2012/08/30 02:50:42]

Why are you changing this?

[yongsheng, 2012/08/30 03:06:30]

The fix for file_path_watcher_linux.cc is because of the below error on Android:
base/files/file_path_watcher_linux.cc:376:77: error: lvalue required as
increment operand.
comps.begin() returns a rvalue.

+  for (++comp; comp != comps.end(); ++comp)
     watches_.push_back(WatchEntry(InotifyReader::kInvalidWatch, *comp));
-  }
+
   watches_.push_back(WatchEntry(InotifyReader::kInvalidWatch,
                                 FilePath::StringType()));
   return UpdateWatches();
 }
 
 void FilePathWatcherImpl::Cancel() {
   if (!delegate_) {
     // Watch was never called, or the |message_loop_| thread is already gone.
     set_cancelled();
     return;
@@ skipping 84 matching lines @@
 }
 
 }  // namespace
 
 FilePathWatcher::FilePathWatcher() {
   impl_ = new FilePathWatcherImpl();
 }
 
 }  // namespace files
 }  // namespace base