Fix uninitialized RGB in GetRGB

BUG=386729
R=palmer@chromium.org

Review URL: https://codereview.chromium.org/366803003

core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp

diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp
index ff44c59..3dad6be 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp
@@ -1362,7 +1362,7 @@
     if (m_pCS == NULL || m_pBuffer == NULL) {
         return FALSE;
     }
-    FX_FLOAT r, g, b;
+    FX_FLOAT r=0.0f, g=0.0f, b=0.0f;
     if (!m_pCS->GetRGB(m_pBuffer, r, g, b)) {
         return FALSE;
     }