Use SkTLazy for ScopedDecodedImageLock's optional paint

cc/playback/display_list_raster_source.cc

Index: cc/playback/display_list_raster_source.cc
diff --git a/cc/playback/display_list_raster_source.cc b/cc/playback/display_list_raster_source.cc
index d1a9fc40d051438e6ba269e0bed53766f240bcd6..c029e1cbb45253a41ccea18b25c9551b0303f9de 100644
--- a/cc/playback/display_list_raster_source.cc
+++ b/cc/playback/display_list_raster_source.cc
@@ -16,6 +16,7 @@
 #include "skia/ext/analysis_canvas.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkPictureRecorder.h"
+#include "third_party/skia/include/core/SkTLazy.h"
 #include "third_party/skia/include/utils/SkNWayCanvas.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 
@@ -145,7 +146,6 @@ class ImageHijackCanvas : public SkNWayCanvas {
                            bool has_perspective,
                            const SkPaint* paint)
         : image_decode_controller_(image_decode_controller),
-          paint_(paint),
           draw_image_(image,
                       RoundOutRect(src_rect),
                       scale,
@@ -155,10 +155,9 @@ class ImageHijackCanvas : public SkNWayCanvas {
           decoded_draw_image_(
               image_decode_controller_->GetDecodedImageForDraw(draw_image_)) {
       DCHECK(image->isLazyGenerated());
-      if (paint) {
-        decoded_paint_ = *paint;
-        decoded_paint_.setFilterQuality(decoded_draw_image_.filter_quality());
-      }
+      if (paint)
+        decoded_paint_.set(*paint)->setFilterQuality(
+            decoded_draw_image_.filter_quality());
     }
 
     ~ScopedDecodedImageLock() {
@@ -170,15 +169,14 @@ class ImageHijackCanvas : public SkNWayCanvas {
       return decoded_draw_image_;
     }
     const SkPaint* decoded_paint() const {
-      return paint_ ? &decoded_paint_ : nullptr;
+      return decoded_paint_.getMaybeNull();
     }
 
    private:
     ImageDecodeController* image_decode_controller_;
-    const SkPaint* paint_;
     DrawImage draw_image_;
     DecodedDrawImage decoded_draw_image_;
-    SkPaint decoded_paint_;
+    SkTLazy<SkPaint> decoded_paint_;

[vmpstr, 2016/02/03 19:30:59]

nit: Can you add a TODO here to use base::Optional when that's available
(https://codereview.chromium.org/1245163002/)

[f(malita), 2016/02/03 20:34:41]

Done.

   };
 
   ImageDecodeController* image_decode_controller_;