Make Web Push use InstanceID tokens instead of GCM registrations

components/gcm_driver/instance_id/fake_gcm_driver_for_instance_id.h

Index: components/gcm_driver/instance_id/fake_gcm_driver_for_instance_id.h
diff --git a/components/gcm_driver/instance_id/fake_gcm_driver_for_instance_id.h b/components/gcm_driver/instance_id/fake_gcm_driver_for_instance_id.h
index c8e9ab7eb9c3efe6428f2c2229eeb37e3a93012e..4ff2c07c9d8a73ded05589c33fe0367ca07d9a0c 100644
--- a/components/gcm_driver/instance_id/fake_gcm_driver_for_instance_id.h
+++ b/components/gcm_driver/instance_id/fake_gcm_driver_for_instance_id.h
@@ -13,12 +13,18 @@
 #include "base/macros.h"
 #include "components/gcm_driver/fake_gcm_driver.h"
 
+namespace base {
+class SequencedTaskRunner;
+}
+
 namespace instance_id {
 
 class FakeGCMDriverForInstanceID : public gcm::FakeGCMDriver,
                                    public gcm::InstanceIDHandler {
  public:
   FakeGCMDriverForInstanceID();
+  explicit FakeGCMDriverForInstanceID(
+      const scoped_refptr<base::SequencedTaskRunner>& blocking_task_runner);
   ~FakeGCMDriverForInstanceID() override;
 
   // FakeGCMDriver overrides: