Make the Sk GL context class an abstract base class

src/gpu/gl/angle/SkANGLEGLContext.cpp

Index: src/gpu/gl/angle/SkANGLEGLContext.cpp
diff --git a/src/gpu/gl/angle/SkANGLEGLContext.cpp b/src/gpu/gl/angle/SkANGLEGLContext.cpp
index 81fccebba0cf08a9932d67a1a88abe1be89d0f41..4914ba55333d70df73ccac437b940ac0db7b6085 100644
--- a/src/gpu/gl/angle/SkANGLEGLContext.cpp
+++ b/src/gpu/gl/angle/SkANGLEGLContext.cpp
@@ -8,21 +8,6 @@
 
 #include "gl/SkANGLEGLContext.h"
 
-SkANGLEGLContext::AutoContextRestore::AutoContextRestore() {
-    fOldEGLContext = eglGetCurrentContext();
-    fOldDisplay = eglGetCurrentDisplay();
-    fOldSurface = eglGetCurrentSurface(EGL_DRAW);
-
-}
-
-SkANGLEGLContext::AutoContextRestore::~AutoContextRestore() {
-    if (fOldDisplay) {
-        eglMakeCurrent(fOldDisplay, fOldSurface, fOldSurface, fOldEGLContext);
-    }
-}
-
-///////////////////////////////////////////////////////////////////////////////
-
 SkANGLEGLContext::SkANGLEGLContext()
     : fContext(EGL_NO_CONTEXT)
     , fDisplay(EGL_NO_DISPLAY)