Implement GPU occluded blur mask filter

src/gpu/SkGpuDevice_drawTexture.cpp

Index: src/gpu/SkGpuDevice_drawTexture.cpp
diff --git a/src/gpu/SkGpuDevice_drawTexture.cpp b/src/gpu/SkGpuDevice_drawTexture.cpp
index 2843c3199699076ad3387cf074bc0f68cb03f420..a92a89ced751c496f944b305f98beb9b5be7c7df 100644
--- a/src/gpu/SkGpuDevice_drawTexture.cpp
+++ b/src/gpu/SkGpuDevice_drawTexture.cpp
@@ -232,6 +232,7 @@ void SkGpuDevice::drawTextureProducerImpl(GrTextureProducer* producer,
                                       clip,
                                       viewMatrix,
                                       rec,
+                                      SkRRect::MakeRect(clippedSrcRect),
                                       SkRRect::MakeRect(clippedDstRect))) {
         return;
     }