Add support for render-ahead

For periods of time during which latency is less important
allow a client to request a deeper render-ahead pipeline.

The latency tradeoff results in less overall visual jank

Test: none, only used by macrobench

Change-Id: I516203b70bdc75b6415fa08bf9c4fb1b598b0102
diff --git a/libs/hwui/Properties.h b/libs/hwui/Properties.h
index 764c502..1a0bdfd 100644
--- a/libs/hwui/Properties.h
+++ b/libs/hwui/Properties.h
@@ -151,6 +151,12 @@
  */
 #define PROPERTY_ENABLE_PARTIAL_UPDATES "debug.hwui.use_partial_updates"
 
+/**
+ * Setting this to "false" will disable the use of the EGL_ANDROID_presentation_time extension
+ * and prevents more precise control over swap behavior & timings.
+ */
+#define PROPERTY_USE_PRESENT_TIME "debug.hwui.use_present_time"
+
 #define PROPERTY_FILTER_TEST_OVERHEAD "debug.hwui.filter_test_overhead"
 
 /**
@@ -220,6 +226,7 @@
     static bool skipEmptyFrames;
     static bool useBufferAge;
     static bool enablePartialUpdates;
+    static bool usePresentTime;
 
     // TODO: Move somewhere else?
     static constexpr float textGamma = 1.45f;