[fsp] Implement storage::WatcherManager for FSP.

[fsp] Implement storage::WatcherManager for FSP.

This patch implements the storage::WatcherManager interface, which simply calls
the Add/RemoveWatcher methods on ProvidedFileSystemInterface implementations.

An additional callback has been added to AddWatcher, so it's easy to notify
WatcherManager about changes. Without that, we would have to observe provided
file system objects and store callbacks passed to WatcherManager::AddWatcher,
which would make the code complex.

Along the way the storage::WatcherManager interface has been refactored to have
consistent naming with FSP watching methods.

TEST=unit_tests: *ProvidedFileSystem*
BUG=248427
Committed: https://crrev.com/340ba2068e2171d80b347fc2ca340446b6c265ec
Cr-Commit-Position: refs/heads/master@{#302229}

[mtomasz, 2014-10-29 09:21:31]

mtomasz@chromium.org changed reviewers:
+ fukino@chromium.org

[mtomasz, 2014-10-29 09:21:32]

@fukino: PTAL. The purpose of this CL is adding watcher_manager.cc and
watcher_manager.h. Besides one callback is added to
fsp::ProvidedFileSystemInterface::AddWatcher. All the rest is simple
refactoring, such as renaming.

Thanks.

[fukino, 2014-10-30 03:42:32]

Thank you. lgtm with nits.

https://codereview.chromium.org/689603002/diff/1/chrome/browser/chromeos/file...
File chrome/browser/chromeos/file_system_provider/fileapi/backend_delegate.h
(right):

https://codereview.chromium.org/689603002/diff/1/chrome/browser/chromeos/file...
chrome/browser/chromeos/file_system_provider/fileapi/backend_delegate.h:25:
class WatcherManager;
This is not necessary?

https://codereview.chromium.org/689603002/diff/1/chrome/browser/chromeos/file...
File
chrome/browser/chromeos/file_system_provider/provided_file_system_unittest.cc
(right):

https://codereview.chromium.org/689603002/diff/1/chrome/browser/chromeos/file...
chrome/browser/chromeos/file_system_provider/provided_file_system_unittest.cc:357:
Log log;
Incorrect indent in this block.

[mtomasz, 2014-10-30 09:50:32]

https://codereview.chromium.org/689603002/diff/1/chrome/browser/chromeos/file...
File chrome/browser/chromeos/file_system_provider/fileapi/backend_delegate.h
(right):

https://codereview.chromium.org/689603002/diff/1/chrome/browser/chromeos/file...
chrome/browser/chromeos/file_system_provider/fileapi/backend_delegate.h:25:
class WatcherManager;
On 2014/10/30 03:42:32, fukino wrote:
> This is not necessary?

Done.

https://codereview.chromium.org/689603002/diff/1/chrome/browser/chromeos/file...
File
chrome/browser/chromeos/file_system_provider/provided_file_system_unittest.cc
(right):

https://codereview.chromium.org/689603002/diff/1/chrome/browser/chromeos/file...
chrome/browser/chromeos/file_system_provider/provided_file_system_unittest.cc:357:
Log log;
On 2014/10/30 03:42:32, fukino wrote:
> Incorrect indent in this block.

Done.

[mtomasz, 2014-10-30 09:50:48]

mtomasz@chromium.org changed reviewers:
+ tzik@chromium.org

[mtomasz, 2014-10-30 09:51:04]

@tzik: PTAL at storage/browser/fileapi/watcher_manager.h. Thanks.

[tzik, 2014-10-31 05:01:31]

lgtm

[mtomasz, 2014-10-31 05:11:15]

The CQ bit was checked by mtomasz@chromium.org

[commit-bot: I haz the power, 2014-10-31 05:12:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/689603002/20001

[commit-bot: I haz the power, 2014-10-31 05:53:58]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2014-10-31 05:54:29]

Patchset 2 (id:??) landed as
https://crrev.com/340ba2068e2171d80b347fc2ca340446b6c265ec
Cr-Commit-Position: refs/heads/master@{#302229}