Move plugins to be stored in HTMLPlugInElement.

third_party/WebKit/Source/core/frame/FrameView.h

Index: third_party/WebKit/Source/core/frame/FrameView.h
diff --git a/third_party/WebKit/Source/core/frame/FrameView.h b/third_party/WebKit/Source/core/frame/FrameView.h
index 5c414251a3bcf7ea3e3e9a35748f5708795a7d50..9702e4ab0055b05bebde8f6ccf3b86a4311db407 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.h
+++ b/third_party/WebKit/Source/core/frame/FrameView.h
@@ -39,6 +39,7 @@
 #include "core/paint/PaintInvalidationCapableScrollableArea.h"
 #include "core/paint/PaintPhase.h"
 #include "core/paint/ScrollbarManager.h"
+#include "core/plugins/PluginView.h"
 #include "platform/FrameViewBase.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/animation/CompositorAnimationHost.h"
@@ -459,12 +460,16 @@ class CORE_EXPORT FrameView final
   HostWindow* getHostWindow() const;
 
   typedef HeapHashSet<Member<FrameViewBase>> ChildrenSet;
+  typedef HeapHashSet<Member<PluginView>> PluginsSet;
 
   // Functions for child manipulation and inspection.
   void setParent(FrameViewBase*) override;
   void removeChild(FrameViewBase*);
   void addChild(FrameViewBase*);
   const ChildrenSet* children() const { return &m_children; }
+  void removePlugin(PluginView*);
+  void addPlugin(PluginView*);
+  const PluginsSet* plugins() const { return &m_plugins; }
 
   // If the scroll view does not use a native widget, then it will have
   // cross-platform Scrollbars. These functions can be used to obtain those
@@ -1137,6 +1142,7 @@ class CORE_EXPORT FrameView final
   bool m_verticalScrollbarLock;
 
   ChildrenSet m_children;
+  PluginsSet m_plugins;
 
   ScrollOffset m_pendingScrollDelta;
   ScrollOffset m_scrollOffset;