Add an option to try and filter out test overhead

Bug: 26912651

By setting debug.hwui.filter_test_overhead to true, hwui's
janktracker will attempt to filter out overhead caused
by the event injection that automated testing uses

Change-Id: I75c8dc5e7798e06e3009baf396108507c7240eec
diff --git a/libs/hwui/Properties.h b/libs/hwui/Properties.h
index 249b5b0..171873d 100644
--- a/libs/hwui/Properties.h
+++ b/libs/hwui/Properties.h
@@ -151,6 +151,8 @@
  */
 #define PROPERTY_ENABLE_PARTIAL_UPDATES "debug.hwui.enable_partial_updates"
 
+#define PROPERTY_FILTER_TEST_OVERHEAD "debug.hwui.filter_test_overhead"
+
 ///////////////////////////////////////////////////////////////////////////////
 // Runtime configuration properties
 ///////////////////////////////////////////////////////////////////////////////
@@ -294,6 +296,10 @@
     // Should be used only by test apps
     static bool waitForGpuCompletion;
 
+    // Should only be set by automated tests to try and filter out
+    // any overhead they add
+    static bool filterOutTestOverhead;
+
 private:
     static ProfileType sProfileType;
     static bool sDisableProfileBars;