return the bytes read, not the total provided



git-svn-id: http://skia.googlecode.com/svn/trunk@1404 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/pipe/SkGPipeRead.cpp b/src/pipe/SkGPipeRead.cpp
index 591b7e9..ecb19fd 100644
--- a/src/pipe/SkGPipeRead.cpp
+++ b/src/pipe/SkGPipeRead.cpp
@@ -562,7 +562,7 @@
     }
 
     if (bytesRead) {
-        *bytesRead = reader.size();
+        *bytesRead = reader.offset();
     }
     return status;
 }