Allow surfaceflinger to run vrflinger

* Allows surface flinger to switch in and out of vr mode

Bug: None
Test: Manually ran various vr test programs.
Change-Id: I15fbba0eb67cbcffeef41be31429550448a1db9c
diff --git a/services/surfaceflinger/DisplayHardware/HWC2.cpp b/services/surfaceflinger/DisplayHardware/HWC2.cpp
index 99a6d71..a25e8a1 100644
--- a/services/surfaceflinger/DisplayHardware/HWC2.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWC2.cpp
@@ -135,8 +135,8 @@
     mSetLayerVisibleRegion(nullptr),
     mSetLayerZOrder(nullptr),
 #else
-Device::Device()
-  : mComposer(std::make_unique<Hwc2::Composer>()),
+Device::Device(bool useVrComposer)
+  : mComposer(std::make_unique<Hwc2::Composer>(useVrComposer)),
 #endif // BYPASS_IHWC
     mCapabilities(),
     mDisplays(),