move the guts of SkMaskFilter.h into SkMaskFilterBase.h

Bug: skia:
Change-Id: I29ad0960156562867429542d3cfbf3d639529cab
Reviewed-on: https://skia-review.googlesource.com/98802
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/tools/debugger/SkDrawCommand.cpp b/tools/debugger/SkDrawCommand.cpp
index 34189fa..c1f0677 100644
--- a/tools/debugger/SkDrawCommand.cpp
+++ b/tools/debugger/SkDrawCommand.cpp
@@ -15,7 +15,7 @@
 #include "SkDashPathEffect.h"
 #include "SkImageFilter.h"
 #include "SkJsonWriteBuffer.h"
-#include "SkMaskFilter.h"
+#include "SkMaskFilterBase.h"
 #include "SkObjectParser.h"
 #include "SkPaintDefaults.h"
 #include "SkPathEffect.h"
@@ -1071,8 +1071,8 @@
                                    UrlDataManager& urlDataManager) {
     SkMaskFilter* maskFilter = paint.getMaskFilter();
     if (maskFilter != nullptr) {
-        SkMaskFilter::BlurRec blurRec;
-        if (maskFilter->asABlur(&blurRec)) {
+        SkMaskFilterBase::BlurRec blurRec;
+        if (as_MFB(maskFilter)->asABlur(&blurRec)) {
             Json::Value blur(Json::objectValue);
             blur[SKDEBUGCANVAS_ATTRIBUTE_SIGMA] = Json::Value(blurRec.fSigma);
             switch (blurRec.fStyle) {