Revert of Sketch splitting SkPicture into an interface and SkBigPicture.

src/gpu/SkGpuDevice.cpp

Index: src/gpu/SkGpuDevice.cpp
diff --git a/src/gpu/SkGpuDevice.cpp b/src/gpu/SkGpuDevice.cpp
index eee93bb0c7905151c04e415246c4dca8d6681d0c..9518600e9948cd681e1bf9f4fb587bc046ccce1c 100644
--- a/src/gpu/SkGpuDevice.cpp
+++ b/src/gpu/SkGpuDevice.cpp
@@ -2014,10 +2014,9 @@
         return false;
     }
 
-    const SkBigPicture::AccelData* data = NULL;
-    if (const SkBigPicture* bp = mainPicture->asSkBigPicture()) {
-        data = bp->accelData();
-    }
+    SkPicture::AccelData::Key key = SkLayerInfo::ComputeKey();
+
+    const SkPicture::AccelData* data = mainPicture->EXPERIMENTAL_getAccelData(key);
     if (!data) {
         return false;
     }