Move all knowledge of X sampling into SkScaledCodec

src/codec/SkSampler.h

Index: src/codec/SkSampler.h
diff --git a/src/codec/SkSampler.h b/src/codec/SkSampler.h
new file mode 100644
index 0000000000000000000000000000000000000000..d7b4c98f235ad1ccb15afa7ff77997aa6d621372
--- /dev/null
+++ b/src/codec/SkSampler.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#ifndef SkSampler_DEFINED
+#define SkSampler_DEFINED
+
+#include "SkTypes.h"
+
+class SkSampler : public SkNoncopyable {
+public:
+    /**
+     *  Update the sampler to sample every sampleX'th pixel. Returns the
+     *  width after sampling.
+     */
+    int setSampleX(int sampleX) {
+        return this->onSetSampleX(sampleX);
+    }
+
+    virtual ~SkSampler() {}
+private:
+    virtual int onSetSampleX(int) = 0;
+};
+
+#endif // SkSampler_DEFINED