Add enterprise enrollment support for fake users.

chrome/browser/chromeos/login/enrollment/enterprise_enrollment_helper_impl.cc

Index: chrome/browser/chromeos/login/enrollment/enterprise_enrollment_helper_impl.cc
diff --git a/chrome/browser/chromeos/login/enrollment/enterprise_enrollment_helper_impl.cc b/chrome/browser/chromeos/login/enrollment/enterprise_enrollment_helper_impl.cc
index 8c18f34f2e3bbd5ff1e18d82d6950e145fcbaa85..87f19a8edd3c1e0143c5e2031d1ab84b9087568c 100644
--- a/chrome/browser/chromeos/login/enrollment/enterprise_enrollment_helper_impl.cc
+++ b/chrome/browser/chromeos/login/enrollment/enterprise_enrollment_helper_impl.cc
@@ -92,7 +92,7 @@ void EnterpriseEnrollmentHelperImpl::EnrollUsingAuthCode(
     bool fetch_additional_token) {
   DCHECK(!started_);
   started_ = true;
-  oauth_fetcher_.reset(new policy::PolicyOAuth2TokenFetcher());
+  oauth_fetcher_.reset(policy::PolicyOAuth2TokenFetcher::CreateInstance());

[Andrew T Wilson (Slow), 2016/03/23 12:37:13]

Why are we going with a static factory method + a static "put into test mode"
API rather than just injecting a mock OAuth2TokenFetcher? That seems like a
cleaner solution than having global state.

[jdufault, 2016/03/23 18:08:23]

I can see two ways to do injection:

1: policy::PolicyOAuth2TokenFetcher::SetAllocatorFn(/* fn that allocates a token
fetcher */)
2: Call into EnterpriseEnrollmentHelperImpl, UserCloudPolicyManagerChromeos, and
WildcardLoginChecker from EnrollmentScreenHandler and set the
PolicyOAuth2TokenFetcher to a fake instance.

With 1, we still have the global state. Given the way that this code is tested
(autotest), the fake implementation has to live in a non-test folder.

With 2, there are a myriad of lifetime issues to deal with and the code now has
to support setting the PolicyOAuth2TokenFetcher multiple ways. For example, in
EnterpriseEnrollmentHelperImpl we allocate a fresh PolicyOAuth2TokenFetcher
instance after receiving a callback from it [1].

I think either the existing solution or solution #1 is fine. If you feel
strongly #2 is the right way to go, we can discuss it more.

1:
https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/chr...

   oauth_fetcher_->StartWithAuthCode(
       auth_code, g_browser_process->system_request_context(),
       base::Bind(&EnterpriseEnrollmentHelperImpl::OnTokenFetched,
@@ -114,11 +114,11 @@ void EnterpriseEnrollmentHelperImpl::ClearAuth(const base::Closure& callback) {
     (new TokenRevoker())->Start(additional_token_);
 
   if (oauth_fetcher_) {
-    if (!oauth_fetcher_->oauth2_access_token().empty())
-      (new TokenRevoker())->Start(oauth_fetcher_->oauth2_access_token());
+    if (!oauth_fetcher_->OAuth2AccessToken().empty())
+      (new TokenRevoker())->Start(oauth_fetcher_->OAuth2AccessToken());
 
-    if (!oauth_fetcher_->oauth2_refresh_token().empty())
-      (new TokenRevoker())->Start(oauth_fetcher_->oauth2_refresh_token());
+    if (!oauth_fetcher_->OAuth2RefreshToken().empty())
+      (new TokenRevoker())->Start(oauth_fetcher_->OAuth2RefreshToken());
 
     oauth_fetcher_.reset();
   } else if (oauth_token_.length()) {
@@ -210,8 +210,8 @@ void EnterpriseEnrollmentHelperImpl::OnTokenFetched(
   }
 
   additional_token_ = token;
-  std::string refresh_token = oauth_fetcher_->oauth2_refresh_token();
-  oauth_fetcher_.reset(new policy::PolicyOAuth2TokenFetcher());
+  std::string refresh_token = oauth_fetcher_->OAuth2RefreshToken();
+  oauth_fetcher_.reset(policy::PolicyOAuth2TokenFetcher::CreateInstance());
   oauth_fetcher_->StartWithRefreshToken(
       refresh_token, g_browser_process->system_request_context(),
       base::Bind(&EnterpriseEnrollmentHelperImpl::OnTokenFetched,