increase margin to 30%

- 20% was not enough for the latest build

bug: 9206671
Change-Id: I210bba6267b2acfbbc58af0c30b2b99ac7121a4a
diff --git a/tests/tests/openglperf/src/android/openglperf/cts/GlVboPerfTest.java b/tests/tests/openglperf/src/android/openglperf/cts/GlVboPerfTest.java
index 8b07b80..ecf198e 100644
--- a/tests/tests/openglperf/src/android/openglperf/cts/GlVboPerfTest.java
+++ b/tests/tests/openglperf/src/android/openglperf/cts/GlVboPerfTest.java
@@ -26,8 +26,8 @@
     private static final String TAG = "GlVboPerfTest";
     private static final int NUM_FRAMES_TO_RENDER = 100;
     private static final long RENDERING_TIMEOUT = 5 * 60;
-    // 10% of fps_no_vbo is allowed to compensate variations in measurement
-    private static final float FPS_COMPARISON_MARGIN = 0.2f;
+    // 30% of fps_no_vbo is allowed to compensate variations in measurement
+    private static final float FPS_COMPARISON_MARGIN = 0.3f;
     // the worst case should be above 70% of the best case
     private static final float FPS_MIN_MAX_COMPARISON_PERCENTILE = 0.7f;