add const to encodePixels pixel parameter

tools/PictureRenderer.cpp

Index: tools/PictureRenderer.cpp
diff --git a/tools/PictureRenderer.cpp b/tools/PictureRenderer.cpp
index 123cc2c5cccee9bc08a2d3486abbdd14f573a13b..5af0538a0dd53f71a05bc8a5860fba8a9e4b64a8 100644
--- a/tools/PictureRenderer.cpp
+++ b/tools/PictureRenderer.cpp
@@ -366,14 +366,10 @@ SkCanvas* RecordPictureRenderer::setupCanvas(int width, int height) {
 
 class PngPixelSerializer : public SkPixelSerializer {
 public:
-    virtual bool onUseEncodedData(const void*, size_t) SK_OVERRIDE { return true; }
-    virtual SkData* onEncodePixels(const SkImageInfo& info, void* pixels,
-                                   size_t rowBytes) SK_OVERRIDE {
-        SkBitmap bm;
-        if (!bm.installPixels(info, pixels, rowBytes)) {
-            return NULL;
-        }
-        return SkImageEncoder::EncodeData(bm, SkImageEncoder::kPNG_Type, 100);
+    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);
     }
 };