Fix founding difference in pdfium_test on AdobeCMYK_to_sRGB

core/fxcodec/codec/fx_codec_jpx_unittest.cpp

Index: core/fxcodec/codec/fx_codec_jpx_unittest.cpp
diff --git a/core/fxcodec/codec/fx_codec_jpx_unittest.cpp b/core/fxcodec/codec/fx_codec_jpx_unittest.cpp
index 820a618f5b83d7b5bfdca0a0cf1869f5e8051a3d..3ef14e62c357db97687d9974ea14f1bf4fb90915 100644
--- a/core/fxcodec/codec/fx_codec_jpx_unittest.cpp
+++ b/core/fxcodec/codec/fx_codec_jpx_unittest.cpp
@@ -19,6 +19,29 @@ static unsigned char stream_data[] = {
     0x84, 0x85, 0x86, 0x87,  // Include some hi-bytes, too.
 };
 
+union Float_t {
+  Float_t(float num = 0.0f) : f(num) {}
+
+  int32_t i;
+  FX_FLOAT f;
+};
+
+TEST(fxcodec, CMYK_Rounding) {
+  // Testing all floats from 0.0 to 1.0 takes about 35 seconds in release
+  // builds and much longer in debug builds, so just test the known-dangerous
+  // range.
+  const FX_FLOAT startValue = 0.001f;
+  const FX_FLOAT endValue = 0.003f;
+  FX_FLOAT R = 0.0f, G = 0.0f, B = 0.0f;
+  // Iterate through floats by incrementing the representation, as discussed in
+  // https://randomascii.wordpress.com/2012/01/23/stupid-float-tricks-2/
+  for (Float_t f = startValue; f.f < endValue; f.i++) {
+    AdobeCMYK_to_sRGB(f.f, f.f, f.f, f.f, R, G, B);
+  }
+  // Check various other 'special' numbers.
+  AdobeCMYK_to_sRGB(0.0f, 0.25f, 0.5f, 1.0f, R, G, B);
+}
+
 TEST(fxcodec, DecodeDataNullDecodeData) {
   unsigned char buffer[16];
   DecodeData* ptr = nullptr;