Add support for GCM subtypes to desktop Instance ID implementation

components/gcm_driver/instance_id/fake_gcm_driver_for_instance_id.cc

Index: components/gcm_driver/instance_id/fake_gcm_driver_for_instance_id.cc
diff --git a/components/gcm_driver/instance_id/fake_gcm_driver_for_instance_id.cc b/components/gcm_driver/instance_id/fake_gcm_driver_for_instance_id.cc
index 0ee7f0b6320f07f2dafc1f3e97a0102ddd48b5cc..0a4ddd521a9e98684a5bf0c12d80bd0e2c61ee12 100644
--- a/components/gcm_driver/instance_id/fake_gcm_driver_for_instance_id.cc
+++ b/components/gcm_driver/instance_id/fake_gcm_driver_for_instance_id.cc
@@ -12,6 +12,18 @@
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/gcm_driver/gcm_client.h"
 
+namespace {
+
+std::string MakeKey(const std::string& app_id,
+                    bool use_subtype,
+                    const std::string& authorized_entity,
+                    const std::string& scope) {
+  return base::IntToString(use_subtype) + ',' + app_id + ',' +
+         authorized_entity + ',' + scope;
+}
+
+}  // namespace
+
 namespace instance_id {
 
 FakeGCMDriverForInstanceID::FakeGCMDriverForInstanceID()
@@ -53,13 +65,14 @@ void FakeGCMDriverForInstanceID::GetInstanceIDData(
 
 void FakeGCMDriverForInstanceID::GetToken(
     const std::string& app_id,
+    bool use_subtype,
     const std::string& authorized_entity,
     const std::string& scope,
     const std::map<std::string, std::string>& options,
     const GetTokenCallback& callback) {
-  std::string token;
-  std::string key = app_id + authorized_entity + scope;
+  std::string key = MakeKey(app_id, use_subtype, authorized_entity, scope);
   auto iter = tokens_.find(key);
+  std::string token;
   if (iter != tokens_.end()) {
     token = iter->second;
   } else {
@@ -73,10 +86,11 @@ void FakeGCMDriverForInstanceID::GetToken(
 
 void FakeGCMDriverForInstanceID::DeleteToken(
     const std::string& app_id,
+    bool use_subtype,
     const std::string& authorized_entity,
     const std::string& scope,
     const DeleteTokenCallback& callback) {
-  std::string key = app_id + authorized_entity + scope;
+  std::string key = MakeKey(app_id, use_subtype, authorized_entity, scope);
   tokens_.erase(key);
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE, base::Bind(callback, gcm::GCMClient::SUCCESS));