pdfviewer: make pdfviewer compile on mac

Review URL: https://codereview.chromium.org/23163007

git-svn-id: http://skia.googlecode.com/svn/trunk@10721 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/experimental/PdfViewer/SkPdfGraphicsState.h b/experimental/PdfViewer/SkPdfGraphicsState.h
index d00c258..d17dc81 100644
--- a/experimental/PdfViewer/SkPdfGraphicsState.h
+++ b/experimental/PdfViewer/SkPdfGraphicsState.h
@@ -359,11 +359,12 @@
 
 // TODO(edisonn): better class design.
 // TODO(edisonn): rename to SkPdfContext
-struct SkPdfContext {
-    std::stack<SkPdfNativeObject*>        fObjectStack;
+class SkPdfContext {
+public:
+    std::stack<SkPdfNativeObject*>  fObjectStack;
     std::stack<SkPdfGraphicsState>  fStateStack;
     SkPdfGraphicsState              fGraphicsState;
-    SkPdfNativeDoc*              fPdfDoc;
+    SkPdfNativeDoc*                 fPdfDoc;
     // TODO(edisonn): the allocator, could be freed after the page is done drawing.
     SkPdfAllocator*                 fTmpPageAllocator;
     SkMatrix                        fOriginalMatrix;