Ash devtools: Add support for changing visibility.

ash/common/devtools/ash_devtools_css_agent.h

Index: ash/common/devtools/ash_devtools_css_agent.h
diff --git a/ash/common/devtools/ash_devtools_css_agent.h b/ash/common/devtools/ash_devtools_css_agent.h
index 84f645d2b940daf7a7d67efd7cd6e39145415f86..e83fdfbeaf6e4e9f51bd479ea1e4372d11fb5c8c 100644
--- a/ash/common/devtools/ash_devtools_css_agent.h
+++ b/ash/common/devtools/ash_devtools_css_agent.h
@@ -43,9 +43,10 @@ class ASH_EXPORT AshDevToolsCSSAgent
   std::unique_ptr<ui::devtools::protocol::CSS::CSSStyle> GetStylesForNode(
       int node_id);
   void InvalidateStyleSheet(int node_id);
-  bool GetBoundsForNodeId(int node_id, gfx::Rect* bounds);
-  bool UpdateBounds(int node_id, const gfx::Rect& bounds);
-
+  bool GetPropertiesForNodeId(int node_id, gfx::Rect* bounds, bool* visible);
+  bool SetPropertiesForNodeId(int node_id,
+                              const gfx::Rect& bounds,
+                              bool visible);
   AshDevToolsDOMAgent* dom_agent_;
 
   DISALLOW_COPY_AND_ASSIGN(AshDevToolsCSSAgent);