Redelivering r3555 to re-add run-time switching between ANGLE and native opengl 

http://codereview.appspot.com/5969044/



git-svn-id: http://skia.googlecode.com/svn/trunk@3578 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/views/SkOSWindow_Android.h b/include/views/SkOSWindow_Android.h
index bdce5d0..5818a0a 100644
--- a/include/views/SkOSWindow_Android.h
+++ b/include/views/SkOSWindow_Android.h
@@ -18,9 +18,15 @@
 public:
     SkOSWindow(void*) {}
     ~SkOSWindow() {}
-    bool attachGL() { return true; }
-    void detachGL() {}
-    void presentGL() {}
+
+    enum SkBackEndTypes {
+        kNone_BackEndType,
+        kNativeGL_BackEndType,
+    };
+
+    bool attach(SkBackEndTypes /* attachType */) { return true; }
+    void detach() {}
+    void present() {}
 
     virtual void onPDFSaved(const char title[], const char desc[],
         const char path[]);