Avoid using an empty scopes set when requesting an OAuth2 access token.

Usign an empty scopes set leads to a server response "code: BAD_REQUEST,
http status: 400, MISSING_SCOPE" on iOS. This CL uses a non-empty
scopes set for the account id tracker.

BUG=NONE

Review URL: https://codereview.chromium.org/472773002

Cr-Commit-Position: refs/heads/master@{#289630}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289630 0039d316-1c4b-4281-b951-d872f2087c98

google_apis/gaia/account_tracker.cc

@@ -274,8 +274,10 @@ AccountIdFetcher::~AccountIdFetcher() {
 }
 
 void AccountIdFetcher::Start() {
+  OAuth2TokenService::ScopeSet scopes;
+  scopes.insert("https://www.googleapis.com/auth/userinfo.profile");
   login_token_request_ = token_service_->StartRequest(
-      account_key_, OAuth2TokenService::ScopeSet(), this);
+      account_key_, scopes, this);
 }
 
 void AccountIdFetcher::OnGetTokenSuccess(