Add GM/slide to simulate Android-style reveal clip

src/ports/SkGlobalInitialization_default.cpp

Index: src/ports/SkGlobalInitialization_default.cpp
diff --git a/src/ports/SkGlobalInitialization_default.cpp b/src/ports/SkGlobalInitialization_default.cpp
index fdafd9609a91a4ff72d562e9ef99c9a5d81e2c26..1f1973649cef5b779927fe70dedf154e0fad2780 100644
--- a/src/ports/SkGlobalInitialization_default.cpp
+++ b/src/ports/SkGlobalInitialization_default.cpp
@@ -24,6 +24,7 @@
 #include "SkDisplacementMapEffect.h"
 #include "SkDropShadowImageFilter.h"
 #include "SkEmbossMaskFilter.h"
+#include "SkGaussianEdgeShader.h"
 #include "SkGradientShader.h"
 #include "SkImageSource.h"
 #include "SkLayerDrawLooper.h"
@@ -89,7 +90,7 @@ void SkFlattenable::PrivateInitializer::InitEffects() {
     SkGradientShader::InitializeFlattenables();
     SkLightingShader::InitializeFlattenables();
     SkNormalSource::InitializeFlattenables();
-
+    SkGaussianEdgeShader::InitializeFlattenables();
 
     // PathEffect
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkArcToPathEffect)