Revise system for checking for uninstantiated proxies

The new pattern is:
  we will "instantiate" pipelines at flush time
  at flush time we will only access the backing GrSurface by peeking

  If instantiation fails we should never try to access the GrSurfaces


Change-Id: I87f7ff41bd0e84d9ca3dbdd61d3361d3d4ceefd6
Reviewed-on: https://skia-review.googlesource.com/17932
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/src/gpu/effects/GrBicubicEffect.cpp b/src/gpu/effects/GrBicubicEffect.cpp
index 70a0096..7d1eba3 100644
--- a/src/gpu/effects/GrBicubicEffect.cpp
+++ b/src/gpu/effects/GrBicubicEffect.cpp
@@ -119,7 +119,8 @@
 void GrGLBicubicEffect::onSetData(const GrGLSLProgramDataManager& pdman,
                                   const GrFragmentProcessor& processor) {
     const GrBicubicEffect& bicubicEffect = processor.cast<GrBicubicEffect>();
-    GrTexture* texture = processor.textureSampler(0).texture();
+    GrTexture* texture = processor.textureSampler(0).peekTexture();
+
     float imageIncrement[2];
     imageIncrement[0] = 1.0f / texture->width();
     imageIncrement[1] = 1.0f / texture->height();