Include SkBitmapDevice for pdf_viewer.

git-svn-id: http://skia.googlecode.com/svn/trunk@12289 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/experimental/PdfViewer/pdf_viewer_main.cpp b/experimental/PdfViewer/pdf_viewer_main.cpp
index 5e9c2e1..fcac67e 100644
--- a/experimental/PdfViewer/pdf_viewer_main.cpp
+++ b/experimental/PdfViewer/pdf_viewer_main.cpp
@@ -5,6 +5,7 @@
  * found in the LICENSE file.
  */
 
+#include "SkBitmapDevice.h"
 #include "SkCanvas.h"
 #include "SkCommandLineFlags.h"
 #include "SkDevice.h"