Initial support for accessibility actions on ARC.

ui/accessibility/ax_tree_id_registry.h

Index: ui/accessibility/ax_tree_id_registry.h
diff --git a/ui/accessibility/ax_tree_id_registry.h b/ui/accessibility/ax_tree_id_registry.h
index 7c16405e6836825f1bc9767b950a64fc30e88658..d983ecd72bfc954f30ba9c3cd220d92a0c238b28 100644
--- a/ui/accessibility/ax_tree_id_registry.h
+++ b/ui/accessibility/ax_tree_id_registry.h
@@ -18,7 +18,16 @@ struct DefaultSingletonTraits;
 
 namespace ui {
 
-// A class which generates a unique id.
+class AXHostDelegate;
+
+// This class generates and saves a runtime id for an accessibility tree.
+// It provides a few distinct forms of generating an id:
+//     - from a frame id (which consists of a process and routing id)
+//     - from a backing |AXHostDelegate| object
+//
+// The first form allows underlying instances to change but refer to the same
+// frame.
+// The second form allows this registry to track the object for later retrieval.
 class AX_EXPORT AXTreeIDRegistry {
  public:
   using FrameID = std::pair<int, int>;
@@ -30,17 +39,22 @@ class AX_EXPORT AXTreeIDRegistry {
   // Get the single instance of this class.
   static AXTreeIDRegistry* GetInstance();
 
-  // Obtains a unique id given a |process_id| and |routing_id|. Placeholder
-  // for full implementation once out of process iframe accessibility finalizes.
+  // Methods for FrameID ax tree id generation, and retrieval.
   AXTreeID GetOrCreateAXTreeID(int process_id, int routing_id);
   FrameID GetFrameID(AXTreeID ax_tree_id);
-  void RemoveAXTreeID(AXTreeID ax_tree_id);
 
-  // Create an id not associated with any process.
-  int CreateID();
+  // Retrieve an |AXHostDelegate|.
+  AXHostDelegate* GetHostDelegate(AXTreeID ax_tree_id);
+
+  void RemoveAXTreeID(AXTreeID ax_tree_id);
 
  private:
   friend struct base::DefaultSingletonTraits<AXTreeIDRegistry>;
+  friend AXHostDelegate;
+
+  // Methods for AXHostDelegate ax tree id generation.
+  AXTreeID GetOrCreateAXTreeID(AXHostDelegate* delegate);
+  void SetDelegateForID(AXHostDelegate* delegate, AXTreeID id);
 
   AXTreeIDRegistry();
   virtual ~AXTreeIDRegistry();
@@ -54,6 +68,9 @@ class AX_EXPORT AXTreeIDRegistry {
   // Maps frames to an accessibility tree via ids.
   std::map<FrameID, AXTreeID> frame_to_ax_tree_id_map_;
 
+  // Maps an id to its host delegate.
+  std::map<AXTreeID, AXHostDelegate*> id_to_host_delegate_;
+
   DISALLOW_COPY_AND_ASSIGN(AXTreeIDRegistry);
 };