Introduce ui.dll / libui.so for the component build.

ui/gfx/color_analysis.h

Index: ui/gfx/color_analysis.h
===================================================================
--- ui/gfx/color_analysis.h	(revision 91577)
+++ ui/gfx/color_analysis.h	(working copy)
@@ -11,6 +11,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/ref_counted_memory.h"
 #include "third_party/skia/include/core/SkColor.h"
+#include "ui/ui_api.h"
 
 namespace color_utils {
 
@@ -18,7 +19,7 @@
 // stubbing out for things like unit tests. Might be useful to pass more
 // arguments into the GetSample method in the future (such as which
 // cluster is being worked on, etc.).
-class KMeanImageSampler {
+class UI_API KMeanImageSampler {
  public:
   virtual int GetSample(int width, int height) = 0;
 
@@ -37,7 +38,7 @@
 };
 
 // This sampler will pick pixels from an evenly spaced grid.
-class GridSampler : public KMeanImageSampler {
+class UI_API GridSampler : public KMeanImageSampler {
   public:
    GridSampler();
    virtual ~GridSampler();
@@ -102,10 +103,10 @@
                                  uint32_t darkness_limit,
                                  uint32_t brightness_limit);
 
-SkColor CalculateKMeanColorOfPNG(scoped_refptr<RefCountedMemory> png,
-                                 uint32_t darkness_limit,
-                                 uint32_t brightness_limit,
-                                 KMeanImageSampler& sampler);
+UI_API SkColor CalculateKMeanColorOfPNG(scoped_refptr<RefCountedMemory> png,
+                                        uint32_t darkness_limit,
+                                        uint32_t brightness_limit,
+                                        KMeanImageSampler& sampler);
 
 }  // namespace color_utils