enable conservative clips for gpudevice

TBR=bsalomon

Author: reed@google.com

Review URL: https://codereview.chromium.org/587793003
diff --git a/samplecode/SampleApp.cpp b/samplecode/SampleApp.cpp
index 08e7240..6ca67bc 100644
--- a/samplecode/SampleApp.cpp
+++ b/samplecode/SampleApp.cpp
@@ -1407,7 +1407,13 @@
         t = SkScalarMul(SkScalarDiv(t, gAnimPeriod), gAnimMag);
         SkMatrix m;
         m.reset();
+#if 1
         m.setPerspY(t);
+#else
+        m.setPerspY(SK_Scalar1 / 1000);
+        m.setSkewX(SkScalarDiv(8, 25));
+        m.dump();
+#endif
         canvas->concat(m);
     }