Create new target to hold gpu test code, enable direct testing of GrEffects in GM.

include/gpu/GrContext.h

Index: include/gpu/GrContext.h
diff --git a/include/gpu/GrContext.h b/include/gpu/GrContext.h
index ab3870915b78f7dcc178e396b76a40fabda40ab3..ae932bd1e4dacd4cd8ea9fc7b0dcd5da2f54035d 100644
--- a/include/gpu/GrContext.h
+++ b/include/gpu/GrContext.h
@@ -33,6 +33,7 @@ class GrPathRenderer;
 class GrResourceEntry;
 class GrResourceCache;
 class GrStencilBuffer;
+class GrTestTarget;
 class GrTextureParams;
 class GrVertexBuffer;
 class GrVertexBufferAllocPool;
@@ -825,6 +826,9 @@ public:
     GrDrawTarget* getTextTarget();
     const GrIndexBuffer* getQuadIndexBuffer() const;
 
+    // Called by tests that draw directly to the context via GrDrawTarget
+    void getTestTarget(GrTestTarget*);
+
     /**
      * Stencil buffers add themselves to the cache using addStencilBuffer. findStencilBuffer is
      * called to check the cache for a SB that matches an RT's criteria.