Make the Sk GL context class an abstract base class

src/gpu/gl/mesa/SkMesaGLContext.cpp

Index: src/gpu/gl/mesa/SkMesaGLContext.cpp
diff --git a/src/gpu/gl/mesa/SkMesaGLContext.cpp b/src/gpu/gl/mesa/SkMesaGLContext.cpp
index 31402c5a3cf79cd3ebcd392ba5a85c1114583867..8c339c7fac4fc50ac837b4155464b92d6a8e7b69 100644
--- a/src/gpu/gl/mesa/SkMesaGLContext.cpp
+++ b/src/gpu/gl/mesa/SkMesaGLContext.cpp
@@ -11,24 +11,6 @@
 #include "gl/SkMesaGLContext.h"
 #include "gl/GrGLDefines.h"
 
-SkMesaGLContext::AutoContextRestore::AutoContextRestore() {
-    fOldContext = (Context)OSMesaGetCurrentContext();
-    if (fOldContext) {
-        OSMesaGetColorBuffer((OSMesaContext)fOldContext,
-                              &fOldWidth, &fOldHeight,
-                              &fOldFormat, &fOldImage);
-    }
-}
-
-SkMesaGLContext::AutoContextRestore::~AutoContextRestore() {
-    if (fOldContext) {
-        OSMesaMakeCurrent((OSMesaContext)fOldContext, fOldImage,
-                          fOldFormat, fOldWidth, fOldHeight);
-    }
-}
-
-///////////////////////////////////////////////////////////////////////////////
-
 SkMesaGLContext::SkMesaGLContext()
     : fContext(static_cast<Context>(NULL))
     , fImage(NULL) {