Fix SkTextBlob offset semantics.

experimental/PdfViewer/SkTrackDevice.h

Index: experimental/PdfViewer/SkTrackDevice.h
diff --git a/experimental/PdfViewer/SkTrackDevice.h b/experimental/PdfViewer/SkTrackDevice.h
index ca4c6894aa2e6e7afef15fdeb1ffacfa5265eb98..8d6a923b18d4af5bdb2f5b9766868d39bf7e3467 100644
--- a/experimental/PdfViewer/SkTrackDevice.h
+++ b/experimental/PdfViewer/SkTrackDevice.h
@@ -120,10 +120,10 @@ protected:
     }
 
     virtual void drawPosText(const SkDraw& dummy1, const void* text, size_t len,
-                             const SkScalar pos[], SkScalar constY,
-                             int scalarsPerPos, const SkPaint& paint) {
+                             const SkScalar pos[], int scalarsPerPos,
+                             const SkPoint& offset, const SkPaint& paint) {
         before();
-        INHERITED::drawPosText(dummy1, text, len, pos, constY, scalarsPerPos, paint);
+        INHERITED::drawPosText(dummy1, text, len, pos, scalarsPerPos, offset, paint);
         after();
     }