Auto-dark mode prototype

Experimental force_dark prototype mode. Enabled
by setting debug.hwui.force_dark to true.

Test: verified nothing changes without prop being set

Change-Id: Ib02f3f1a9c591cab1f312b827451f04c782c2f41
diff --git a/libs/hwui/Properties.cpp b/libs/hwui/Properties.cpp
index 0338a3a..17bec19 100644
--- a/libs/hwui/Properties.cpp
+++ b/libs/hwui/Properties.cpp
@@ -60,6 +60,7 @@
 bool Properties::filterOutTestOverhead = false;
 bool Properties::disableVsync = false;
 bool Properties::skpCaptureEnabled = false;
+bool Properties::forceDarkMode = false;
 bool Properties::enableRTAnimations = true;
 
 bool Properties::runningInEmulator = false;
@@ -146,6 +147,8 @@
 
     runningInEmulator = property_get_bool(PROPERTY_QEMU_KERNEL, false);
 
+    forceDarkMode = property_get_bool(PROPERTY_FORCE_DARK, false);
+
     return (prevDebugLayersUpdates != debugLayersUpdates) || (prevDebugOverdraw != debugOverdraw) ||
            (prevDebugStencilClip != debugStencilClip);
 }