PolicyManager: New System provider.

The system provider exposes information about the device from
crossystem and the kernel boot command line options.

BUG=chromium:338587
TEST=Unit tests.

Change-Id: I2837a97740b63562155717cfe6a12fad69fd8cea
Reviewed-on: https://chromium-review.googlesource.com/191121
Reviewed-by: Alex Deymo <deymo@chromium.org>
Tested-by: Alex Deymo <deymo@chromium.org>
Commit-Queue: Alex Deymo <deymo@chromium.org>
diff --git a/policy_manager/real_state.cc b/policy_manager/real_state.cc
index 2f9f3cc..8b0086f 100644
--- a/policy_manager/real_state.cc
+++ b/policy_manager/real_state.cc
@@ -12,9 +12,11 @@
 
 RealState::RealState(RandomProvider* random_provider,
                      ShillProvider* shill_provider,
+                     SystemProvider* system_provider,
                      TimeProvider* time_provider) {
   set_random_provider(random_provider);
   set_shill_provider(shill_provider);
+  set_system_provider(system_provider);
   set_time_provider(time_provider);
 }