Adds a function computing image color covariance.

ui/gfx/color_analysis.h

Index: ui/gfx/color_analysis.h
diff --git a/ui/gfx/color_analysis.h b/ui/gfx/color_analysis.h
index 6201874e80c3c2aadfab0fff01b65a3d1bec3152..a61f75f6ba62221746ff17734fa5614b0460cdac 100644
--- a/ui/gfx/color_analysis.h
+++ b/ui/gfx/color_analysis.h
@@ -11,6 +11,7 @@
 #include "base/memory/ref_counted_memory.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/base/ui_export.h"
+#include "ui/gfx/matrix3_f.h"
 
 class SkBitmap;
 
@@ -98,6 +99,11 @@ UI_EXPORT SkColor CalculateKMeanColorOfPNG(
 // reasonable defaults for |darkness_limit|, |brightness_limit| and |sampler|.
 UI_EXPORT SkColor CalculateKMeanColorOfBitmap(const SkBitmap& bitmap);
 
+// Compute color covariance matrix for the input bitmap. 4x4 matrix is used

[Alexei Svitkine (slow), 2013/02/12 19:19:29]

Your comment about a 4x4 matrix being used for the return type doesn't seem
accurate...

[motek., 2013/02/12 19:28:56]

Done.

+// as the return type for convenience (easier to apply to 3d points). Only 3
+// first dimensions are used (correspond to RGB channels).
+UI_EXPORT gfx::Matrix3F ComputeColorCovariance(const SkBitmap& bitmap);
+
 }  // namespace color_utils
 
 #endif  // UI_GFX_COLOR_ANALYSIS_H_