Rename GrInOrderDrawBuffer to GrBufferedDrawTarget

BUG=skia:

Review URL: https://codereview.chromium.org/1261033002
diff --git a/samplecode/SampleManyRects.cpp b/samplecode/SampleManyRects.cpp
index a570853..9c9e985 100644
--- a/samplecode/SampleManyRects.cpp
+++ b/samplecode/SampleManyRects.cpp
@@ -14,7 +14,7 @@
 #include "SkView.h"
 
 /**
- * Animated sample used to develop batched rect implementation in GrInOrderDrawBuffer.
+ * Animated sample used to develop batched rect implementation in GrBufferedDrawTarget.
  */
 class ManyRectsView : public SampleView {
 private: