Initialize colour values

The colour values returned from the ColorSpace GetRBG methods may not
have set a value. This CL updates the CPDF_MeshStream to always
initialize the values to 0 so they can't be used uninitialized.

Bug: chromium:714074
Change-Id: Id2db5eabe31d2ff19f9330b2bc5c681680cf461d
Reviewed-on: https://pdfium-review.googlesource.com/4450
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>

core/fpdfapi/page/cpdf_meshstream.cpp

diff --git a/core/fpdfapi/page/cpdf_meshstream.cpp b/core/fpdfapi/page/cpdf_meshstream.cpp
index c173bc6..ac93513 100644
--- a/core/fpdfapi/page/cpdf_meshstream.cpp
+++ b/core/fpdfapi/page/cpdf_meshstream.cpp
@@ -204,9 +204,9 @@
                          (m_ColorMax[i] - m_ColorMin[i]) / m_ComponentMax;
   }
 
-  float r;
-  float g;
-  float b;
+  float r = 0.0;
+  float g = 0.0;
+  float b = 0.0;
   if (m_funcs.empty()) {
     m_pCS->GetRGB(color_value, &r, &g, &b);
     return std::tuple<float, float, float>(r, g, b);