Support multiple PDF rendering backends in the GM

R=epoger@google.com, vandebo@chromium.org

Review URL: https://codereview.chromium.org/21669004

git-svn-id: http://skia.googlecode.com/svn/trunk@10841 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/mixedxfermodes.cpp b/gm/mixedxfermodes.cpp
index f057672..645143a 100644
--- a/gm/mixedxfermodes.cpp
+++ b/gm/mixedxfermodes.cpp
@@ -125,6 +125,11 @@
         }
     }
 
+    virtual uint32_t onGetFlags() const {
+        // Skip PDF rasterization since rendering this PDF takes forever.
+        return kSkipPDFRasterization_Flag;
+    }
+
 private:
     enum {
         kNumShapes = 100,