Outline SkImageFilter Make methods

src/core/SkLocalMatrixImageFilter.h

 /*
  * Copyright 2015 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkLocalMatrixImageFilter_DEFINED
 #define SkLocalMatrixImageFilter_DEFINED
 
 #include "SkImageFilter.h"
 
 /**
  *  Wraps another imagefilter + matrix, such that using this filter will give the same result
  *  as using the wrapped filter with the matrix applied to its context.
  */
 class SkLocalMatrixImageFilter : public SkImageFilter {
 public:
-    static sk_sp<SkImageFilter> Make(const SkMatrix& localM, sk_sp<SkImageFilter> input) {
-        if (!input) {
-            return nullptr;
-        }
-        if (localM.getType() & (SkMatrix::kAffine_Mask | SkMatrix::kPerspective_Mask)) {
-            return nullptr;
-        }
-        if (localM.isIdentity()) {
-            return input;
-        }
-        return sk_sp<SkImageFilter>(new SkLocalMatrixImageFilter(localM, input));
-    }
+    static sk_sp<SkImageFilter> Make(const SkMatrix& localM, sk_sp<SkImageFilter> input);
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkLocalMatrixImageFilter)
 
 #ifdef SK_SUPPORT_LEGACY_IMAGEFILTER_PTR
     static SkImageFilter* Create(const SkMatrix& localM, SkImageFilter* input) {
         return Make(localM, sk_sp<SkImageFilter>(SkSafeRef(input))).release();
     }
 #endif
 
 protected:
     void flatten(SkWriteBuffer&) const override;
     sk_sp<SkSpecialImage> onFilterImage(SkSpecialImage* source, const Context&,
                                         SkIPoint* offset) const override;
     SkIRect onFilterBounds(const SkIRect& src, const SkMatrix&, MapDirection) const override;
 
 private:
     SkLocalMatrixImageFilter(const SkMatrix& localM, sk_sp<SkImageFilter> input);
 
     SkMatrix fLocalM;
 
     typedef SkImageFilter INHERITED;
 };
 
 #endif