remove external header for SkModeColorFilter

src/core/SkModeColorFilter.h

Index: src/core/SkModeColorFilter.h
diff --git a/include/effects/SkModeColorFilter.h b/src/core/SkModeColorFilter.h
similarity index 82%
rename from include/effects/SkModeColorFilter.h
rename to src/core/SkModeColorFilter.h
index 06eec43572bd5264dc6bd839ba390bffeb978c52..9fa7717b84d7bf8d93cd9caf685f07e095a02dcf 100644
--- a/include/effects/SkModeColorFilter.h
+++ b/src/core/SkModeColorFilter.h
@@ -1,18 +1,16 @@
 /*
- * Copyright 2015 Google Inc.
+ * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
-#ifndef SkModeColorFilter_DEFINED
-#define SkModeColorFilter_DEFINED
-
 #include "SkColorFilter.h"
-#include "SkColorPriv.h"
-#include "SkString.h"
 #include "SkXfermode.h"
 
+#ifndef SkModeColorFilter_DEFINED
+#define SkModeColorFilter_DEFINED
+
 class SkModeColorFilter : public SkColorFilter {
 public:
     static SkColorFilter* Create(SkColor color, SkXfermode::Mode mode) {
@@ -28,12 +26,7 @@ public:
     void filterSpan(const SkPMColor shader[], int count, SkPMColor result[]) const override;
 
 #ifndef SK_IGNORE_TO_STRING
-    void toString(SkString* str) const override {
-        str->append("SkModeColorFilter: color: 0x");
-        str->appendHex(fColor);
-        str->append(" mode: ");
-        str->append(SkXfermode::ModeName(fMode));
-    }
+    void toString(SkString* str) const override;
 #endif
 
 #if SK_SUPPORT_GPU
@@ -59,6 +52,8 @@ private:
 
     void updateCache();
 
+    friend class SkColorFilter;
+
     typedef SkColorFilter INHERITED;
 };