Preserve texture compression when saving a revised skp from debugger

tools/sk_tool_utils.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef sk_tool_utils_DEFINED
 #define sk_tool_utils_DEFINED
 
 #include "SkColor.h"
+#include "SkImageEncoder.h"
 #include "SkImageInfo.h"
+#include "SkPixelSerializer.h"
 #include "SkTypeface.h"
 
 class SkBitmap;
 class SkCanvas;
 class SkPaint;
 class SkShader;
 class SkTestFont;
 
 namespace sk_tool_utils {
 
@@ skipping 25 matching lines @@
     void draw_checkerboard(SkCanvas* canvas,
                            SkColor color1,
                            SkColor color2,
                            int size);
 
     /** A default checkerboard. */
     inline void draw_checkerboard(SkCanvas* canvas) {
         sk_tool_utils::draw_checkerboard(canvas, 0xFF999999, 0xFF666666, 8);
     }
 
+    // Encodes to PNG, unless there is already encoded data, in which case that gets
+    // used.
+    class PngPixelSerializer : public SkPixelSerializer {
+    public:
+        bool onUseEncodedData(const void*, size_t) SK_OVERRIDE { return true; }
+        SkData* onEncodePixels(const SkImageInfo& info, const void* pixels,
+                               size_t rowBytes) SK_OVERRIDE {
+            return SkImageEncoder::EncodeData(info, pixels, rowBytes,
+                                              SkImageEncoder::kPNG_Type, 100);
+        }
+    };
+
 }  // namespace sk_tool_utils
 
 #endif  // sk_tool_utils_DEFINED