Trace FrameTreeNode Snapshots

content/browser/frame_host/frame_tree_node.h

Index: content/browser/frame_host/frame_tree_node.h
diff --git a/content/browser/frame_host/frame_tree_node.h b/content/browser/frame_host/frame_tree_node.h
index c108da5eebae48e680dc5b879e0556276f238a6e..fda8ecd3dfc21c11f62186c8b2e87fcaff0f4d1a 100644
--- a/content/browser/frame_host/frame_tree_node.h
+++ b/content/browser/frame_host/frame_tree_node.h
@@ -32,7 +32,8 @@ class RenderFrameHostImpl;
 // of those frames. We are mirroring this tree in the browser process. This
 // class represents a node in this tree and is a wrapper for all objects that
 // are frame-specific (as opposed to page-specific).
-class CONTENT_EXPORT FrameTreeNode {
+class CONTENT_EXPORT FrameTreeNode :
+  public base::trace_event::TraceLog::EnabledStateObserver {
  public:
   class Observer {
    public:
@@ -64,7 +65,7 @@ class CONTENT_EXPORT FrameTreeNode {
                 const std::string& unique_name,
                 const blink::WebFrameOwnerProperties& frame_owner_properties);
 
-  ~FrameTreeNode();
+  ~FrameTreeNode() override;
 
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
@@ -267,11 +268,17 @@ class CONTENT_EXPORT FrameTreeNode {
   // FrameTreeNode.
   void BeforeUnloadCanceled();
 
+  // TraceLog::EnabledStateObserver
+  void OnTraceLogEnabled() override;
+  void OnTraceLogDisabled() override {}
+
  private:
   class OpenerDestroyedObserver;
 
   void set_parent(FrameTreeNode* parent) { parent_ = parent; }
 
+  void TraceSnapshot() const;
+
   // The next available browser-global FrameTreeNode ID.
   static int next_frame_tree_node_id_;