HDR: Do nonlinear blending in the compositor

ui/compositor/compositor.h

 // Copyright (c) 2012 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.
 
 #ifndef UI_COMPOSITOR_COMPOSITOR_H_
 #define UI_COMPOSITOR_COMPOSITOR_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 93 matching lines @@
   // Inform the display corresponding to this compositor if it is visible. When
   // false it does not need to produce any frames. Visibility is reset for each
   // call to CreateCompositorFrameSink.
   virtual void SetDisplayVisible(ui::Compositor* compositor, bool visible) = 0;
 
   // Resize the display corresponding to this compositor to a particular size.
   virtual void ResizeDisplay(ui::Compositor* compositor,
                              const gfx::Size& size) = 0;
 
   // Set the output color profile into which this compositor should render.
-  virtual void SetDisplayColorSpace(ui::Compositor* compositor,
-                                    const gfx::ColorSpace& color_space) = 0;
+  virtual void SetDisplayColorSpace(
+      ui::Compositor* compositor,
+      const gfx::ColorSpace& blending_color_space,
+      const gfx::ColorSpace& output_color_space) = 0;
 
   virtual void SetAuthoritativeVSyncInterval(ui::Compositor* compositor,
                                              base::TimeDelta interval) = 0;
   // Mac path for transporting vsync parameters to the display.  Other platforms
   // update it via the BrowserCompositorCompositorFrameSink directly.
   virtual void SetDisplayVSyncParameters(ui::Compositor* compositor,
                                          base::TimeTicks timebase,
                                          base::TimeDelta interval) = 0;
 
   virtual void SetOutputIsSecure(Compositor* compositor, bool secure) = 0;
@@ skipping 302 matching lines @@
   // layers on.
   float device_scale_factor_;
 
   bool locks_will_time_out_;
   CompositorLock* compositor_lock_;
 
   LayerAnimatorCollection layer_animator_collection_;
   scoped_refptr<cc::AnimationTimeline> animation_timeline_;
   std::unique_ptr<ScopedAnimationDurationScaleMode> slow_animations_;
 
-  gfx::ColorSpace color_space_;
+  gfx::ColorSpace output_color_space_;
+  gfx::ColorSpace blending_color_space_;
 
   base::WeakPtrFactory<Compositor> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Compositor);
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_COMPOSITOR_H_