Export the texture pixelref classes via SK_API.  This is necessary to reference
them from another DLL in the windows shared build.

Review URL:  http://codereview.appspot.com/5646056/


git-svn-id: http://skia.googlecode.com/svn/trunk@3155 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/gpu/SkGrTexturePixelRef.h b/include/gpu/SkGrTexturePixelRef.h
index 720f130..ab92eff 100644
--- a/include/gpu/SkGrTexturePixelRef.h
+++ b/include/gpu/SkGrTexturePixelRef.h
@@ -21,7 +21,7 @@
  *  Common baseclass that implements onLockPixels() by calling onReadPixels().
  *  Since it has a copy, it always returns false for onLockPixelsAreWritable().
  */
-class SkROLockPixelsPixelRef : public SkPixelRef {
+class SK_API SkROLockPixelsPixelRef : public SkPixelRef {
 public:
     SkROLockPixelsPixelRef();
     virtual ~SkROLockPixelsPixelRef();
@@ -40,7 +40,7 @@
 /**
  *  PixelRef that wraps a GrTexture
  */
-class SkGrTexturePixelRef : public SkROLockPixelsPixelRef {
+class SK_API SkGrTexturePixelRef : public SkROLockPixelsPixelRef {
 public:
             SkGrTexturePixelRef(GrTexture*);
     virtual ~SkGrTexturePixelRef();
@@ -63,7 +63,7 @@
 /**
  *  PixelRef that wraps a GrRenderTarget
  */
-class SkGrRenderTargetPixelRef : public SkROLockPixelsPixelRef {
+class SK_API SkGrRenderTargetPixelRef : public SkROLockPixelsPixelRef {
 public:
             SkGrRenderTargetPixelRef(GrRenderTarget* rt);
     virtual ~SkGrRenderTargetPixelRef();