Revert of Create a unified UIElement interface for Widget, View and Window.

ash/devtools/ash_devtools_css_agent.h

Index: ash/devtools/ash_devtools_css_agent.h
diff --git a/ash/devtools/ash_devtools_css_agent.h b/ash/devtools/ash_devtools_css_agent.h
index 9225475f65636cb691b66a7624c5736a1585cceb..f4027ed087f8b157417016593bc2288eecc03424 100644
--- a/ash/devtools/ash_devtools_css_agent.h
+++ b/ash/devtools/ash_devtools_css_agent.h
@@ -5,10 +5,9 @@
 #ifndef ASH_DEVTOOLS_ASH_DEVTOOLS_CSS_AGENT_H_
 #define ASH_DEVTOOLS_ASH_DEVTOOLS_CSS_AGENT_H_
 
-#include "ash/ash_export.h"
 #include "ash/devtools/ash_devtools_dom_agent.h"
-#include "base/macros.h"
 #include "components/ui_devtools/CSS.h"
+#include "ui/views/widget/widget_observer.h"
 
 namespace ash {
 namespace devtools {
@@ -21,7 +20,7 @@
   explicit AshDevToolsCSSAgent(AshDevToolsDOMAgent* dom_agent);
   ~AshDevToolsCSSAgent() override;
 
-  // CSS::Backend:
+  // CSS::Backend
   ui::devtools::protocol::Response enable() override;
   ui::devtools::protocol::Response disable() override;
   ui::devtools::protocol::Response getMatchedStylesForNode(
@@ -35,8 +34,10 @@
           ui::devtools::protocol::Array<ui::devtools::protocol::CSS::CSSStyle>>*
           result) override;
 
-  // AshDevToolsDOMAgentObserver:
-  void OnNodeBoundsChanged(int node_id) override;
+  // AshDevToolsDOMAgentObserver
+  void OnWindowBoundsChanged(aura::Window* window) override;
+  void OnWidgetBoundsChanged(views::Widget* widget) override;
+  void OnViewBoundsChanged(views::View* view) override;
 
  private:
   std::unique_ptr<ui::devtools::protocol::CSS::CSSStyle> GetStylesForNode(