Added pretty printers for some Ink Drop enums.

ui/views/animation/ink_drop_hover.cc

Index: ui/views/animation/ink_drop_hover.cc
diff --git a/ui/views/animation/ink_drop_hover.cc b/ui/views/animation/ink_drop_hover.cc
index af98e614f5978c893fd276d1663a8fe4ff5c6ede..b0d08fd21bb96db231901621e5a2a1261b831d25 100644
--- a/ui/views/animation/ink_drop_hover.cc
+++ b/ui/views/animation/ink_drop_hover.cc
@@ -24,6 +24,18 @@ const float kHiddenOpacity = 0.0f;
 
 }  // namespace
 
+std::string ToString(const InkDropHover::AnimationType& animation_type) {
+  switch (animation_type) {
+    case InkDropHover::FADE_IN:
+      return std::string("FADE_IN");
+    case InkDropHover::FADE_OUT:
+      return std::string("FADE_OUT");
+  }
+  NOTREACHED()
+      << "Should never be reached but is necessary for some compilers.";
+  return std::string("UNKNOWN");
+}
+
 InkDropHover::InkDropHover(const gfx::Size& size,
                            int corner_radius,
                            const gfx::Point& center_point,