cefclient: OSR accessibility enhancements (see issue #2604)

- Implement multi-tree support (e.g. page with iframes contains several trees)
- Implement OnAccessibilityLocationChange support
- Add scroll offset calculation
- Fix new Chromium tree layout parsing
- Fix uninitialized OsrAXNode::offset_container_id_
- Fix Windows non ascii AxName, AxValue, AxDescription representation

tests/cefclient/browser/osr_accessibility_node.h

@@ -33,12 +33,17 @@ class OsrAccessibilityHelper;
 class OsrAXNode {
  public:
   // Create and return the platform specific OsrAXNode Object.
-  static OsrAXNode* CreateNode(CefRefPtr<CefDictionaryValue> value,
+  static OsrAXNode* CreateNode(int treeId,
+                               int nodeId,
+                               CefRefPtr<CefDictionaryValue> value,
                                OsrAccessibilityHelper* helper);
 
   // Update Value.
   void UpdateValue(CefRefPtr<CefDictionaryValue> value);
 
+  // UpdateLocation
+  void UpdateLocation(CefRefPtr<CefDictionaryValue> value);
+
   // Fire a platform-specific notification that an event has occurred on
   // this object.
   void NotifyAccessibilityEvent(std::string event_type) const;
@@ -58,13 +63,15 @@ class OsrAXNode {
     return accessibility_helper_;
   }
 
-  int GetChildCount() const { return static_cast<int>(child_ids_.size()); }
+  int GetChildCount() const;
 
   // Return the Child at the specified index
   OsrAXNode* ChildAtIndex(int index) const;
 
   const CefString& AxRole() const { return role_; }
 
+  int OsrAXTreeId() const { return tree_id_; }
+
   int OsrAXNodeId() const { return node_id_; }
 
   const CefString& AxValue() const { return value_; }
@@ -82,15 +89,20 @@ class OsrAXNode {
   void SetParent(OsrAXNode* parent);
 
  protected:
-  OsrAXNode(CefRefPtr<CefDictionaryValue> value,
+  OsrAXNode(int treeId,
+            int nodeId,
+            CefRefPtr<CefDictionaryValue> value,
             OsrAccessibilityHelper* helper);
 
+  int tree_id_;
   int node_id_;
+  int child_tree_id_;
   CefString role_;
   CefString value_;
   CefString name_;
   CefString description_;
   CefRect location_;
+  CefPoint scroll_;
   std::vector<int> child_ids_;
   CefNativeAccessible* platform_accessibility_;
   OsrAXNode* parent_;