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/mock_hardware.h b/common/mock_hardware.h
index 826b3b3..1c4253a 100644
--- a/common/mock_hardware.h
+++ b/common/mock_hardware.h
@@ -36,6 +36,9 @@
     ON_CALL(*this, IsNormalBootMode())
       .WillByDefault(testing::Invoke(&fake_,
             &FakeHardware::IsNormalBootMode));
+    ON_CALL(*this, AreDevFeaturesEnabled())
+      .WillByDefault(testing::Invoke(&fake_,
+            &FakeHardware::AreDevFeaturesEnabled));
     ON_CALL(*this, IsOOBEEnabled())
       .WillByDefault(testing::Invoke(&fake_,
             &FakeHardware::IsOOBEEnabled));