Move chromeos::GDataFileSystem::GetCacheDirectoryPath and GetCacheFilePath implementation to GDataC…

Move chromeos::GDataFileSystem::GetCacheDirectoryPath and GetCacheFilePath implementation to GDataCache

This is a part of an effort to move cache related code from GDataFileSystem to GDataCache.
GDataFileSystem::GetCacheDirectoryPath and GetCacheFilePath are still provided to serve a number of existing users, this is a temporary solution.
cache_paths() and kMountedArchiveFileExtension are exposed as a temporary solution.
Tests for these methods are not moved from GDataFileSystemTest in this change, they will be removed and reimplemented once we finish moving other methods and get ready to do more comprehensive test in GDataCacheTest.

BUG=131756
TEST=unit_tests --gtest_filter="GData*"

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=141223

[satorux1, 2012-06-08 15:10:54]

https://chromiumcodereview.appspot.com/10545084/diff/1/chrome/browser/chromeo...
File chrome/browser/chromeos/gdata/gdata_cache.h (right):

https://chromiumcodereview.appspot.com/10545084/diff/1/chrome/browser/chromeo...
chrome/browser/chromeos/gdata/gdata_cache.h:122: FilePath
GetCacheDirectoryPath(CacheSubDirectoryType sub_dir_type) const;
The class used to be a pure interface class where all non-static member
functions were virtual. I have feeling that having non-virtual functions in the
class is not desirable, but I don't have a bigger picture of how this class
should look like after the large code move from GDataFileSystem is complete.

That said, I'm ok with having a non-virtual function in this  class for now.
Once the code move is complete, we can do major refacotoring as needed.

[satorux1, 2012-06-08 15:11:12]

LGTM

[commit-bot: I haz the power, 2012-06-08 15:12:33]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/hashimoto@chromium.org/10545084/1

[commit-bot: I haz the power, 2012-06-08 17:25:53]

Change committed as 141223