Fix uninitialized value in CPDF_ColorStateData

BUG=411161
R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/560673002
diff --git a/core/include/fpdfapi/fpdf_pageobj.h b/core/include/fpdfapi/fpdf_pageobj.h
index 307fb16..f211254 100644
--- a/core/include/fpdfapi/fpdf_pageobj.h
+++ b/core/include/fpdfapi/fpdf_pageobj.h
@@ -165,7 +165,7 @@
 {
 public:
 
-    CPDF_ColorStateData() {}
+    CPDF_ColorStateData(): m_FillRGB(0), m_StrokeRGB(0) {}
 
     CPDF_ColorStateData(const CPDF_ColorStateData& src);