Make 0-texture GrCustomStages work.

Review URL: http://codereview.appspot.com/6448080/



git-svn-id: http://skia.googlecode.com/svn/trunk@4858 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/gl/GrGLProgram.h b/src/gpu/gl/GrGLProgram.h
index b6c224c..18d97d5 100644
--- a/src/gpu/gl/GrGLProgram.h
+++ b/src/gpu/gl/GrGLProgram.h
@@ -276,10 +276,9 @@
 
     struct StageUniforms {
         UniformHandle fTextureMatrixUni;
-        UniformHandle fSamplerUni;
+        SkTArray<UniformHandle, true> fSamplerUniforms;
         StageUniforms() {
             fTextureMatrixUni = GrGLUniformManager::kInvalidUniformHandle;
-            fSamplerUni = GrGLUniformManager::kInvalidUniformHandle;
         }
     };