Introduces new SingleTextureEffect base class for GrCustomStage objects.
This class tracks the texture that the object uses. A future commit will get rid of the
GrTexture pointer currenty stored in the GrDrawState, allowing us to have CustomStages
*without* textures.

Requires gyp change on next roll.

http://codereview.appspot.com/6306097/



git-svn-id: http://skia.googlecode.com/svn/trunk@4576 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gyp/gpu.gyp b/gyp/gpu.gyp
index cabd331..4a708d8 100644
--- a/gyp/gpu.gyp
+++ b/gyp/gpu.gyp
@@ -293,6 +293,8 @@
         '../src/gpu/effects/GrGradientEffects.h',
         '../src/gpu/effects/GrMorphologyEffect.cpp',
         '../src/gpu/effects/GrMorphologyEffect.h',
+        '../src/gpu/effects/GrSingleTextureEffect.cpp',
+        '../src/gpu/effects/GrSingleTextureEffect.h',
 
         '../src/gpu/gl/GrGLCaps.cpp',
         '../src/gpu/gl/GrGLCaps.h',