color: Fix accidental partial color conversion

ui/gfx/color_transform.cc

 // Copyright (c) 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gfx/color_transform.h"
 
 #include <algorithm>
 #include <cmath>
 #include <list>
 #include <memory>
@@ skipping 714 matching lines @@
 
 ColorTransformInternal::ColorTransformInternal(const ColorSpace& src,
                                                const ColorSpace& dst,
                                                Intent intent)
     : src_(src), dst_(dst) {
   // If no source color space is specified, do no transformation.
   // TODO(ccameron): We may want dst assume sRGB at some point in the future.
   if (!src_.IsValid())
     return;
 
-  ScopedQcmsProfile src_profile = GetQCMSProfileIfNecessary(src_);
-  ScopedQcmsProfile dst_profile = GetQCMSProfileIfNecessary(dst_);
+  // If the dst profile is not set, then do only YUV to RGB conversion, so

[hubbe, 2017/02/21 22:46:49]

I'm afraid I don't get this.
When does this happen?

[ccameron, 2017/02/22 00:08:29]

This happens whenever media::kVideoColorManagement is not true and color
conversion is not enabled.

In that case we have ColorTransform do the YUV->RGB conversion for us (instead
of doing it manually in GLRenderer).

[hubbe, 2017/02/22 00:10:05]

Can we add some more meat to the comment to describe this?

[ccameron, 2017/02/22 00:30:48]

Done.

+  // ignore any ICC profiles.
+  ScopedQcmsProfile src_profile;
+  ScopedQcmsProfile dst_profile;
+  if (dst.IsValid()) {
+    src_profile = GetQCMSProfileIfNecessary(src_);
+    dst_profile = GetQCMSProfileIfNecessary(dst_);
+  }
   bool has_src_profile = !!src_profile;
   bool has_dst_profile = !!dst_profile;
 
   if (src_profile) {
     steps_.push_back(base::MakeUnique<QCMSColorTransform>(
         std::move(src_profile), GetXYZD50Profile()));
   }
 
   AppendColorSpaceToColorSpaceTransform(
       has_src_profile ? ColorSpace::CreateXYZD50() : src_,
@@ skipping 65 matching lines @@
     const ColorSpace& to,
     Intent intent) {
   return std::unique_ptr<ColorTransform>(
       new ColorTransformInternal(from, to, intent));
 }
 
 ColorTransform::ColorTransform() {}
 ColorTransform::~ColorTransform() {}
 
 }  // namespace gfx