VizDevTools: Providing updates of a FrameSink tree

FrameSinkElement implements FrameSinkObserver interface and handles all
the events for updating the tree.

Bug: 816802
Change-Id: I6552281672cda18f611c65971aa56eea7aa13a00
Reviewed-on: https://chromium-review.googlesource.com/1113018
Commit-Queue: Yi Xu <yiyix@chromium.org>
Reviewed-by: kylechar <kylechar@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584290}

components/ui_devtools/ui_element.h

@@ -31,6 +31,7 @@ class UI_DEVTOOLS_EXPORT UIElement {
   int node_id() const { return node_id_; };
   std::string GetTypeName() const;
   UIElement* parent() const { return parent_; };
+  void set_parent(UIElement* parent) { parent_ = parent; };
   UIElementDelegate* delegate() const { return delegate_; };
   UIElementType type() const { return type_; };
   const std::vector<UIElement*>& children() const { return children_; };

components/ui_devtools/viz_views/dom_agent_viz.h

@@ -10,21 +10,37 @@
 #include "components/ui_devtools/DOM.h"
 #include "components/ui_devtools/dom_agent.h"
 #include "components/viz/common/surfaces/frame_sink_id.h"
+#include "components/viz/service/frame_sinks/frame_sink_observer.h"
 
 namespace viz {
 class FrameSinkManagerImpl;
 }
 
 namespace ui_devtools {
+class FrameSinkElement;
 
-class DOMAgentViz : public DOMAgent {
+class DOMAgentViz : public viz::FrameSinkObserver, public DOMAgent {
  public:
   explicit DOMAgentViz(viz::FrameSinkManagerImpl* frame_sink_manager);
   ~DOMAgentViz() override;
 
+  // viz::FrameSinkObserver:
+  void OnRegisteredFrameSinkId(const viz::FrameSinkId& frame_sink_id) override;
+  void OnInvalidatedFrameSinkId(const viz::FrameSinkId& frame_sink_id) override;
+  void OnCreatedCompositorFrameSink(const viz::FrameSinkId& frame_sink_id,
+                                    bool is_root) override;
+  void OnDestroyedCompositorFrameSink(
+      const viz::FrameSinkId& frame_sink_id) override;
+  void OnRegisteredFrameSinkHierarchy(
+      const viz::FrameSinkId& parent_frame_sink_id,
+      const viz::FrameSinkId& child_frame_sink_id) override;
+  void OnUnregisteredFrameSinkHierarchy(
+      const viz::FrameSinkId& parent_frame_sink_id,
+      const viz::FrameSinkId& child_frame_sink_id) override;
+
  private:
   std::unique_ptr<protocol::DOM::Node> BuildTreeForFrameSink(
-      UIElement* frame_sink_element,
+      FrameSinkElement* frame_sink_element,
       const viz::FrameSinkId& frame_sink_id);
 
   // DOM::Backend:
@@ -36,6 +52,10 @@ class DOMAgentViz : public DOMAgent {
   std::unique_ptr<protocol::DOM::Node> BuildTreeForUIElement(
       UIElement* ui_element) override;
 
+  // Removes the |child| subtree from the |parent| subtree and destroys every
+  // element in the |child| subtree.
+  void DestroyChildSubtree(UIElement* parent, UIElement* child);
+
   // Every time the frontend disconnects we don't destroy DOMAgent so once we
   // establish the connection again we need to clear the FrameSinkId sets
   // because they may carry obsolete data. Then we initialize these with alive
@@ -50,13 +70,33 @@ class DOMAgentViz : public DOMAgent {
   // Mark a FrameSink that has |frame_sink_id| and all its subtree as attached.
   void SetAttachedFrameSink(const viz::FrameSinkId& frame_sink_id);
 
-  // These sets are used to create and update the DOM tree.
-  base::flat_set<viz::FrameSinkId> registered_frame_sink_ids_;
-  base::flat_set<viz::FrameSinkId> client_connected_frame_sinks_;
-
-  // This is used to track created FrameSinkElements and will be used for
-  // updates in a FrameSink tree.
-  base::flat_map<viz::FrameSinkId, UIElement*> frame_sink_elements_;
+  // We delete the FrameSinkElements in the subtree rooted at |root| from
+  // |frame_sink_elements_| and attach all its children to the root_element().
+  void RemoveFrameSinkSubtree(UIElement* root);
+
+  // Remove FrameSinkElements for subtree rooted at |element| from the tree
+  // |frame_sink_elements_|.
+  void RemoveFrameSinkElement(UIElement* element);
+
+  // These sets are used to create and update the DOM tree. We add/remove
+  // registered FrameSinks to |registered_frame_sink_ids_to_is_connected_| when
+  // FrameSink is registered/invalidated and initialize the bool to false to
+  // indicate that the FrameSink is not created yet. Then when a |frame_sink| is
+  // created/destroyed, we update |registered_frame_sink_ids_to_is_connected_|
+  // of |frame_sink| true or false accordingly. When we get events
+  // registered/unregistered hierarchy we don't change these sets because we
+  // detach a subtree from one node and attach it to another node and the list
+  // of registered/created FrameSinkIds doesn't change.
+  // TODO(yiyix): Removes this map because it saves duplicated information as
+  // |frame_sink_elements_|.
+  base::flat_map<viz::FrameSinkId, bool>
+      registered_frame_sink_ids_to_is_connected_;
+
+  // This is used to track created FrameSinkElements in a FrameSink tree. Every
+  // time we register/invalidate a FrameSinkId, create/destroy a FrameSink,
+  // register/unregister hierarchy we change this set, because these actions
+  // involve deleting and adding elements.
+  base::flat_map<viz::FrameSinkId, FrameSinkElement*> frame_sink_elements_;
 
   // This is used to denote attached FrameSinks.
   base::flat_set<viz::FrameSinkId> attached_frame_sinks_;

components/ui_devtools/viz_views/frame_sink_element.h

@@ -26,6 +26,17 @@ class FrameSinkElement : public UIElement {
                    bool is_client_connected);
   ~FrameSinkElement() override;
 
+  // Used by DOMAgentViz on updates when element is already present
+  // in a tree but its properties need to be changed.
+  void SetRegistered(bool is_registered) { is_registered_ = is_registered; }
+  void SetClientConnected(bool is_client_connected) {
+    is_client_connected_ = is_client_connected;
+  }
+  void SetRoot(bool is_root) { is_root_ = is_root; }
+
+  bool is_registered() const { return is_registered_; }
+  bool is_client_connected() const { return is_client_connected_; }
+
   // UIElement:
   std::vector<std::pair<std::string, std::string>> GetCustomProperties()
       const override;