Allow passing in a list of scopes to the access token fetcher class.

Allow passing in a list of scopes to the access token fetcher class.
This enables full ability to dosn scope: given a login scoped refresh token,
get an access token for any scope (or more accurately any list of scopes).

Add tests for MakeGetAccessTokenBody (and fix a bug that the test discovered - missing &).
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=112158

[Munjal (Google), 2011-11-29 20:20:22]

Sailesh, after this patch is committed, you will get an access token from this
fetcher (by passing in the Picasa scope) and then use that access token.

[sail, 2011-11-29 20:43:10]

http://codereview.chromium.org/8728038/diff/1/chrome/common/net/gaia/oauth2_a...
File chrome/common/net/gaia/oauth2_access_token_fetcher.cc (right):

http://codereview.chromium.org/8728038/diff/1/chrome/common/net/gaia/oauth2_a...
chrome/common/net/gaia/oauth2_access_token_fetcher.cc:97: source_(source),
What should I pass for source? This doesn't seem to be used currently.

[Munjal (Google), 2011-11-29 21:58:09]

http://codereview.chromium.org/8728038/diff/1/chrome/common/net/gaia/oauth2_a...
File chrome/common/net/gaia/oauth2_access_token_fetcher.cc (right):

http://codereview.chromium.org/8728038/diff/1/chrome/common/net/gaia/oauth2_a...
chrome/common/net/gaia/oauth2_access_token_fetcher.cc:97: source_(source),
On 2011/11/29 20:43:11, sail wrote:
> What should I pass for source? This doesn't seem to be used currently.

Done. Good catch. I removed it.

[sail, 2011-11-29 22:57:18]

lgtm