Add consistency to treatment of |id_token| in IdentityTestEnv APIs

I just noticed that the variant that issues an access token for all
accounts has an overload for passing |id_token|, while the variant that
specifies an account has it as an optional argument. Let's use the
optional argument approach for both, as we're shortly going to need
to add another optional argument for scopes.

Bug: 798699
Change-Id: I610cc5bf1ba596b92ccd7d18ad6aa3bcc32ac246
Reviewed-on: https://chromium-review.googlesource.com/c/1329794
Commit-Queue: Colin Blundell <blundell@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607212}

services/identity/public/cpp/identity_test_environment.cc

@@ -272,14 +272,6 @@ void IdentityTestEnvironment::SetAutomaticIssueOfAccessTokens(bool grant) {
   token_service_->set_auto_post_fetch_response_on_message_loop(grant);
 }
 
-void IdentityTestEnvironment::
-    WaitForAccessTokenRequestIfNecessaryAndRespondWithToken(
-        const std::string& token,
-        const base::Time& expiration) {
-  WaitForAccessTokenRequestIfNecessary(base::nullopt);
-  token_service_->IssueTokenForAllPendingRequests(token, expiration);
-}
-
 void IdentityTestEnvironment::
     WaitForAccessTokenRequestIfNecessaryAndRespondWithToken(
         const std::string& token,

services/identity/public/cpp/identity_test_environment.h

@@ -132,37 +132,27 @@ class IdentityTestEnvironment : public IdentityManager::DiagnosticsObserver {
   // already occurred and has not been matched by a previous call to this or
   // other WaitFor... method, or (b) will occur in the future. In the latter
   // case, waits until the access token request occurs.
+  // |id_token| is an uncommonly-needed parameter that contains extra
+  // information regarding the user's currently-registered services; if this
+  // means nothing to you, you don't need to concern yourself with it.
   // NOTE: This method behaves this way to allow IdentityTestEnvironment to be
   // agnostic with respect to whether access token requests are handled
   // synchronously or asynchronously in the production code.
   // NOTE: This version is suitable for use in the common context where access
   // token requests are only being made for one account. If you need to
   // disambiguate requests coming for different accounts, see the version below.
-  void WaitForAccessTokenRequestIfNecessaryAndRespondWithToken(
-      const std::string& token,
-      const base::Time& expiration);
-
-  // Issues |token| in response to any access token request that either has (a)
-  // already occurred and has not been matched by a previous call to this or
-  // other WaitFor... method, or (b) will occur in the future. In the latter
-  // case, waits until the access token request occurs.
-  // NOTE: This method behaves this way to allow IdentityTestEnvironment to be
-  // agnostic with respect to whether access token requests are handled
-  // synchronously or asynchronously in the production code.
-  // NOTE: This version is suitable for use in the common context where access
-  // token requests are only being made for one account. If you need to
-  // disambiguate requests coming for different accounts, see the version below.
-  // NOTE: This version allows passing the uncommon id_token parameter which is
-  // needed to test some cases where checking for that extra info is required.
   void WaitForAccessTokenRequestIfNecessaryAndRespondWithToken(
       const std::string& token,
       const base::Time& expiration,
-      const std::string& id_token);
+      const std::string& id_token = std::string());
 
   // Issues |token| in response to an access token request for |account_id| that
   // either already occurred and has not been matched by a previous call to this
   // or other WaitFor... method , or (b) will occur in the future. In the latter
   // case, waits until the access token request occurs.
+  // |id_token| is an uncommonly-needed parameter that contains extra
+  // information regarding the user's currently-registered services; if this
+  // means nothing to you, you don't need to concern yourself with it.
   // NOTE: This method behaves this way to allow
   // IdentityTestEnvironment to be agnostic with respect to whether access token
   // requests are handled synchronously or asynchronously in the production
@@ -175,7 +165,7 @@ class IdentityTestEnvironment : public IdentityManager::DiagnosticsObserver {
 
   // Issues |error| in response to any access token request that either has (a)
   // already occurred and has not been matched by a previous call to this or
-  // other WaitFor... method, or (b) will occur in the future via  In the latter
+  // other WaitFor... method, or (b) will occur in the future. In the latter
   // case, waits until the access token request occurs.
   // NOTE: This method behaves this way to allow IdentityTestEnvironment to be
   // agnostic with respect to whether access token requests are handled