Revert of Revert of Fix SkTextBlob offset semantics.

src/gpu/SkGpuDevice.h

Index: src/gpu/SkGpuDevice.h
diff --git a/src/gpu/SkGpuDevice.h b/src/gpu/SkGpuDevice.h
index 41b53b12138327d4f5835c28869444e7cfcabfb4..f19d2cb62b1faa8f93e89f7209c3fc9bd1f0370f 100644
--- a/src/gpu/SkGpuDevice.h
+++ b/src/gpu/SkGpuDevice.h
@@ -90,8 +90,8 @@
     virtual void drawText(const SkDraw&, const void* text, size_t len,
                           SkScalar x, SkScalar y, const SkPaint&) SK_OVERRIDE;
     virtual void drawPosText(const SkDraw&, const void* text, size_t len,
-                             const SkScalar pos[], SkScalar constY,
-                             int scalarsPerPos, const SkPaint&) SK_OVERRIDE;
+                             const SkScalar pos[], int scalarsPerPos,
+                             const SkPoint& offset, const SkPaint&) SK_OVERRIDE;
     virtual void drawTextOnPath(const SkDraw&, const void* text, size_t len,
                                 const SkPath& path, const SkMatrix* matrix,
                                 const SkPaint&) SK_OVERRIDE;