color: Don't use QCMS for transforms unless necessary

ui/gfx/color_transform.cc

Index: ui/gfx/color_transform.cc
diff --git a/ui/gfx/color_transform.cc b/ui/gfx/color_transform.cc
index 49a3026c895e13c33926b613c6724dc4e45d723c..cb751436ad4d82b657d0ef13ce752d3ab82943c3 100644
--- a/ui/gfx/color_transform.cc
+++ b/ui/gfx/color_transform.cc
@@ -277,6 +277,11 @@ class ColorTransformInternal : public ColorTransform {
                                              ColorTransform::Intent intent);
   void Simplify();
 
+  // Retrieve the ICC profile from which |color_space| was created, only if that
+  // is a more precise representation of the color space than the primaries and
+  // transfer function in |color_space|.
+  ScopedQcmsProfile GetQCMSProfileIfNecessary(const ColorSpace& color_space);
+
   std::list<std::unique_ptr<ColorTransformStep>> steps_;
 };
 
@@ -540,6 +545,10 @@ void ColorTransformInternal::AppendColorSpaceToColorSpaceTransform(
     ColorSpace from,
     const ColorSpace& to,
     ColorTransform::Intent intent) {
+  // If the source was not specified, assume that it was sRGB.
+  if (!from.IsValid())

[hubbe, 2017/02/16 01:28:29]

It would be really cool if we could just do DCHECK(from.NoUnspecifiedValues())
here :)

[ccameron, 2017/02/16 01:58:47]

Maybe one day :D

I rebased this patch on top of the one that changes the default values, which
made this change go away.

+    from = gfx::ColorSpace::CreateSRGB();
+
   if (intent == ColorTransform::Intent::INTENT_PERCEPTUAL) {
     switch (from.transfer_) {
       case ColorSpace::TransferID::UNSPECIFIED:
@@ -654,9 +663,10 @@ class QCMSColorTransform : public ColorTransformStep {
   ScopedQcmsProfile to_;
 };
 
-ScopedQcmsProfile GetQCMSProfileIfAvailable(const ColorSpace& color_space) {
-  ICCProfile icc_profile = ICCProfile::FromColorSpace(color_space);
-  if (icc_profile.GetData().empty())
+ScopedQcmsProfile ColorTransformInternal::GetQCMSProfileIfNecessary(
+    const ColorSpace& color_space) {
+  ICCProfile icc_profile;
+  if (!ICCProfile::FromId(color_space.icc_profile_id_, true, &icc_profile))
     return nullptr;
   return ScopedQcmsProfile(qcms_profile_from_memory(
       icc_profile.GetData().data(), icc_profile.GetData().size()));
@@ -686,8 +696,8 @@ ScopedQcmsProfile GetXYZD50Profile() {
 ColorTransformInternal::ColorTransformInternal(const ColorSpace& from,
                                                const ColorSpace& to,
                                                Intent intent) {
-  ScopedQcmsProfile from_profile = GetQCMSProfileIfAvailable(from);
-  ScopedQcmsProfile to_profile = GetQCMSProfileIfAvailable(to);
+  ScopedQcmsProfile from_profile = GetQCMSProfileIfNecessary(from);
+  ScopedQcmsProfile to_profile = GetQCMSProfileIfNecessary(to);
   bool has_from_profile = !!from_profile;
   bool has_to_profile = !!to_profile;