Preserve texture compression when saving a revised skp from debugger

tools/sk_tool_utils.h

Index: tools/sk_tool_utils.h
diff --git a/tools/sk_tool_utils.h b/tools/sk_tool_utils.h
index 48c71e7e74315fa521110f80ba51bb2f956192ff..8754de69af126fe8c2c72b785c12240a9ac27648 100644
--- a/tools/sk_tool_utils.h
+++ b/tools/sk_tool_utils.h
@@ -9,7 +9,9 @@
 #define sk_tool_utils_DEFINED
 
 #include "SkColor.h"
+#include "SkImageEncoder.h"
 #include "SkImageInfo.h"
+#include "SkPixelSerializer.h"
 #include "SkTypeface.h"
 
 class SkBitmap;
@@ -55,6 +57,18 @@ namespace sk_tool_utils {
         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