Make HardwareChromeOS own debugd.

It only exists in Chrome OS, Brillo doesn't have it.

Test: ./update_engine_unittests
Bug: 28800946

Change-Id: I49d2024dbad5e0bf78bbc479f97dabb569b32c56
diff --git a/common/hardware_interface.h b/common/hardware_interface.h
index f5f900e..316ad3d 100644
--- a/common/hardware_interface.h
+++ b/common/hardware_interface.h
@@ -44,6 +44,9 @@
   // features.
   virtual bool IsNormalBootMode() const = 0;
 
+  // Returns whether the developer features are enabled.
+  virtual bool AreDevFeaturesEnabled() const = 0;
+
   // Returns whether the device has an OOBE flow that the user must go through
   // before getting non-critical updates. Use IsOOBEComplete() to determine if
   // that flow is complete.