Refactor read and write buffers.

src/effects/gradients/SkLinearGradient.cpp

Index: src/effects/gradients/SkLinearGradient.cpp
diff --git a/src/effects/gradients/SkLinearGradient.cpp b/src/effects/gradients/SkLinearGradient.cpp
index 70452962acb4a24425f15f708768d7a44a086193..bd66f7ca849644daa0e42b69af29000f1b0238ad 100644
--- a/src/effects/gradients/SkLinearGradient.cpp
+++ b/src/effects/gradients/SkLinearGradient.cpp
@@ -59,13 +59,13 @@ SkLinearGradient::SkLinearGradient(const SkPoint pts[2], const Descriptor& desc)
     pts_to_unit_matrix(pts, &fPtsToUnit);
 }
 
-SkLinearGradient::SkLinearGradient(SkFlattenableReadBuffer& buffer)
+SkLinearGradient::SkLinearGradient(SkReadBuffer& buffer)
     : INHERITED(buffer)
     , fStart(buffer.readPoint())
     , fEnd(buffer.readPoint()) {
 }
 
-void SkLinearGradient::flatten(SkFlattenableWriteBuffer& buffer) const {
+void SkLinearGradient::flatten(SkWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
     buffer.writePoint(fStart);
     buffer.writePoint(fEnd);