[qcms] Apply qcms color matching api to Blink images

third_party/WebKit/Source/platform/image-decoders/jpeg/JPEGImageDecoder.cpp

Index: third_party/WebKit/Source/platform/image-decoders/jpeg/JPEGImageDecoder.cpp
diff --git a/third_party/WebKit/Source/platform/image-decoders/jpeg/JPEGImageDecoder.cpp b/third_party/WebKit/Source/platform/image-decoders/jpeg/JPEGImageDecoder.cpp
index 1704bc29a369e42928497664f45dfbc8681c827c..dba37f772bd3d69b20d69e0ab2d77a602d3ea3c7 100644
--- a/third_party/WebKit/Source/platform/image-decoders/jpeg/JPEGImageDecoder.cpp
+++ b/third_party/WebKit/Source/platform/image-decoders/jpeg/JPEGImageDecoder.cpp
@@ -650,11 +650,19 @@ public:
         qcms_profile* inputProfile = qcms_profile_from_memory(colorProfile.data(), colorProfile.size());
         if (!inputProfile)
             return;
+
         // We currently only support color profiles for RGB profiled images.
         ASSERT(rgbData == qcms_profile_get_color_space(inputProfile));
-        qcms_data_type dataFormat = hasAlpha ? QCMS_DATA_RGBA_8 : QCMS_DATA_RGB_8;
+
+        if (qcms_profile_match(inputProfile, deviceProfile)) {
+            qcms_profile_release(inputProfile);

[Justin Novosad, 2015/12/15 21:10:59]

There is no test to verify that this code path is actually used. It would make
sense to have a unit test that verifies that m_transform does not get set under
conditions where this optimization is expected to kick in. Same thing for the
other decoders.

[Noel Gordon, 2015/12/16 05:00:32]

Actually the number of tests that changed behavior tell me otherwise.  Applying
color transforms where none is needed, introduces color  distortion.  We no
longer do that, and plenty of tests said so.  As I said in the change
description, "all were progressions", and some person had to stare at all the
pixel results of 99 tests to confirm that. That was me.  We could always improve
coverage, but 99 tests seems pretty good to me at this time.

[Justin Novosad, 2015/12/16 05:25:26]

Okay, so that proves the patch is working. And I suppose we can rely on tests in
qcms to guard against regressions in qcms_profile_match

+            return;
+        }
+
         // FIXME: Don't force perceptual intent if the image profile contains an intent.
+        qcms_data_type dataFormat = hasAlpha ? QCMS_DATA_RGBA_8 : QCMS_DATA_RGB_8;
         m_transform = qcms_transform_create(inputProfile, dataFormat, deviceProfile, dataFormat, QCMS_INTENT_PERCEPTUAL);
+
         qcms_profile_release(inputProfile);
     }
 #endif