Add brightness/grayscale animations and use them for OOBE boot transition

ui/compositor/layer_animation_element.h

Index: ui/compositor/layer_animation_element.h
diff --git a/ui/compositor/layer_animation_element.h b/ui/compositor/layer_animation_element.h
index d1e305e796e9be0e5dbd0742da49df5f9784a62f..89bf26f7499d5b0383f3675d9acc3cdc634fed4f 100644
--- a/ui/compositor/layer_animation_element.h
+++ b/ui/compositor/layer_animation_element.h
@@ -28,7 +28,9 @@ class COMPOSITOR_EXPORT LayerAnimationElement {
     TRANSFORM = 0,
     BOUNDS,
     OPACITY,
-    VISIBILITY
+    VISIBILITY,
+    BRIGHTNESS,
+    GRAYSCALE
   };
 
   struct COMPOSITOR_EXPORT TargetValue {
@@ -40,6 +42,8 @@ class COMPOSITOR_EXPORT LayerAnimationElement {
     Transform transform;
     float opacity;
     bool visibility;
+    float brightness;
+    float grayscale;
   };
 
   typedef std::set<AnimatableProperty> AnimatableProperties;
@@ -83,6 +87,18 @@ class COMPOSITOR_EXPORT LayerAnimationElement {
       bool visibility,
       base::TimeDelta duration);
 
+  // Creates an element that transitions to the given brightness.
+  // The caller owns the return value.
+  static LayerAnimationElement* CreateBrightnessElement(
+      float brightness,
+      base::TimeDelta duration);
+
+  // Creates an element that transitions to the given grayscale value.
+  // The caller owns the return value.
+  static LayerAnimationElement* CreateGrayscaleElement(
+      float grayscale,
+      base::TimeDelta duration);
+
   // Creates an element that pauses the given properties. The caller owns the
   // return value.
   static LayerAnimationElement* CreatePauseElement(