Make a bunch of virtuals in GrDrawTarget and GrGpu private. Subclasses shouldn't call them directly.

R=robertphillips@google.com
Review URL: https://codereview.appspot.com/7228048

git-svn-id: http://skia.googlecode.com/svn/trunk@7413 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/gl/GrGpuGL_program.cpp b/src/gpu/gl/GrGpuGL_program.cpp
index 7e0d0b0..b8d5f08 100644
--- a/src/gpu/gl/GrGpuGL_program.cpp
+++ b/src/gpu/gl/GrGpuGL_program.cpp
@@ -317,7 +317,7 @@
     GrIRect* devRect = NULL;
     GrIRect devClipBounds;
     if (drawState.isClipState()) {
-        fClip->getConservativeBounds(drawState.getRenderTarget(), &devClipBounds);
+        this->getClip()->getConservativeBounds(drawState.getRenderTarget(), &devClipBounds);
         devRect = &devClipBounds;
     }
     // This must come after textures are flushed because a texture may need