Add glReadBuffer to GrGLInterface.

Review URL: http://codereview.appspot.com/4841048/





git-svn-id: http://skia.googlecode.com/svn/trunk@2034 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gpu/src/win/GrGLDefaultInterface_win.cpp b/gpu/src/win/GrGLDefaultInterface_win.cpp
index 05f5414..1bf0457 100644
--- a/gpu/src/win/GrGLDefaultInterface_win.cpp
+++ b/gpu/src/win/GrGLDefaultInterface_win.cpp
@@ -72,6 +72,7 @@
             gDefaultInterface.fMatrixMode = glMatrixMode;
             gDefaultInterface.fPixelStorei = glPixelStorei;
             gDefaultInterface.fPointSize = glPointSize;
+            gDefaultInterface.fReadBuffer = glReadBuffer;
             gDefaultInterface.fReadPixels = glReadPixels;
             gDefaultInterface.fScissor = glScissor;
             gDefaultInterface.fShadeModel = glShadeModel;