Add extension API test for FileSystem API.

Add extension API test for FileSystem API.

BUG=61534
TEST=ExtensionApiTest.FileAPI

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=68418

[ericu, 2010-12-01 00:58:45]

http://codereview.chromium.org/5392001/diff/1/chrome/test/data/extensions/api...
File chrome/test/data/extensions/api_test/fileapi/background.html (right):

http://codereview.chromium.org/5392001/diff/1/chrome/test/data/extensions/api...
chrome/test/data/extensions/api_test/fileapi/background.html:10:
fileSystem.root.getDirectory('dir', {create:true},
Is there ever any cleanup done between tests?  Could this be sitting around from
a previous run?

I'm not sure it matters; we're still demonstrating API access, just not that we
can do something that increases quota usage.

[kinuko, 2010-12-01 03:17:59]

http://codereview.chromium.org/5392001/diff/1/chrome/test/data/extensions/api...
File chrome/test/data/extensions/api_test/fileapi/background.html (right):

http://codereview.chromium.org/5392001/diff/1/chrome/test/data/extensions/api...
chrome/test/data/extensions/api_test/fileapi/background.html:10:
fileSystem.root.getDirectory('dir', {create:true},
On 2010/12/01 00:58:46, ericu wrote:
> Is there ever any cleanup done between tests?  Could this be sitting around
from
> a previous run?

Once we add ExtensionDataDeleter I believe the data goes away between tests.

Meanwhile I also added local clean-up code in tab.html.
(background.html and tab.html usually have different execution timings (when
it's facing users) and I was not sure if creating a file in background.html and
deleting it in tab.html is a good idea.)

[ericu, 2010-12-04 02:23:02]

Kinuko, I'm sorry not to have responded faster--this slipped off my radar.

LGTM