Fix up all the easy virtual ... SK_OVERRIDE cases.

tools/render_pdfs_main.cpp

Index: tools/render_pdfs_main.cpp
diff --git a/tools/render_pdfs_main.cpp b/tools/render_pdfs_main.cpp
index 5e3385ef9b5edae9b0d91370794fd23b9d694a89..678787780bff7846af76cee0baa95046a4386454 100644
--- a/tools/render_pdfs_main.cpp
+++ b/tools/render_pdfs_main.cpp
@@ -122,11 +122,11 @@ namespace {
 class NullWStream : public SkWStream {
 public:
     NullWStream() : fBytesWritten(0) { }
-    virtual bool write(const void*, size_t size) SK_OVERRIDE {
+    bool write(const void*, size_t size) SK_OVERRIDE {
         fBytesWritten += size;
         return true;
     }
-    virtual size_t bytesWritten() const SK_OVERRIDE { return fBytesWritten; }
+    size_t bytesWritten() const SK_OVERRIDE { return fBytesWritten; }
     size_t fBytesWritten;
 };
 }  // namespace