Reimplement automation API on top of C++-backed AXTree.

chrome/common/extensions/api/automation.idl

Index: chrome/common/extensions/api/automation.idl
diff --git a/chrome/common/extensions/api/automation.idl b/chrome/common/extensions/api/automation.idl
index a0d81168b5847bed4c67be3f2c885a7fb1ded784..426163e1b62dc2758f8087600f8db0b3fa739444 100644
--- a/chrome/common/extensions/api/automation.idl
+++ b/chrome/common/extensions/api/automation.idl
@@ -317,8 +317,6 @@
     // The role of this node.
     automation.RoleType role;
 
-    // TODO(aboxhall): expose states as mixins instead
-
     // The $(ref:automation.StateType)s describing this node.
     object state;
 
@@ -369,96 +367,21 @@
     // name, via the $(ref:automation.AutomationNode.name) attribute.
     AutomationNode[] labelledBy;
 
-    // The nodes, if any, which are to be considered children of this node but
-    // are not children in the DOM tree.
-    AutomationNode[] owns;
-
-    // TODO(aboxhall): Make this private?
-
-    // A collection of this node's other attributes.
-    object? attributes;
-
-    // The index of this node in its parent node's list of children. If this is
-    // the root node, this will be undefined.
-    long? indexInParent;
-
-    AutomationNode[] children;
-    AutomationNode parent;
-    AutomationNode firstChild;
-    AutomationNode lastChild;
-    AutomationNode previousSibling;
-    AutomationNode nextSibling;
-
-    // Does the default action based on this node's role. This is generally
-    // the same action that would result from clicking the node such as
-    // expanding a treeitem, toggling a checkbox, selecting a radiobutton,
-    // or activating a button.
-    static void doDefault();
-
-    // Places focus on this node.
-    static void focus();
-
-    // Scrolls this node to make it visible.
-    static void makeVisible();
-
-    // Sets selection within a text field.
-    static void setSelection(long startIndex, long endIndex);
-
-    // Shows the context menu resulting from a right click on this node.
-    static void showContextMenu();
-
-    // Adds a listener for the given event type and event phase.
-    static void addEventListener(
-        EventType eventType, AutomationListener listener, boolean capture);
-
-    // Removes a listener for the given event type and event phase.
-    static void removeEventListener(
-        EventType eventType, AutomationListener listener, boolean capture);
-
-    // Gets the first node in this node's subtree which matches the given CSS
-    // selector and is within the same DOM context.
-    //
-    // If this node doesn't correspond directly with an HTML node in the DOM,
-    // querySelector will be run on this node's nearest HTML node ancestor. Note
-    // that this may result in the query returning a node which is not a
-    // descendant of this node.
-    //
-    // If the selector matches a node which doesn't directly correspond to an
-    // automation node (for example an element within an ARIA widget, where the
-    // ARIA widget forms one node of the automation tree, or an element which
-    // is hidden from accessibility via hiding it using CSS or using
-    // aria-hidden), this will return the nearest ancestor which does correspond
-    // to an automation node.
-    static void domQuerySelector(DOMString selector, QueryCallback callback);
-
-    // Finds the first AutomationNode in this node's subtree which matches the
-    // given search parameters.
-    static AutomationNode find(FindParams params);
-
-    // Finds all the AutomationNodes in this node's subtree which matches the
-    // given search parameters.
-    static AutomationNode[] findAll(FindParams params);
-
-    // Returns whether this node matches the given $(ref:automation.FindParams).
-    static boolean matches(FindParams params);
-  };
-
-  dictionary ActiveDescendantMixin {
     // The node referred to by <code>aria-activedescendant</code>, where
     // applicable
     AutomationNode activedescendant;
-  };
 
-  // Attributes which are mixed in to an AutomationNode if it is a link.
-  dictionary LinkMixins {
-    // TODO(aboxhall): Add visited state
+    //
+    // Link attributes.
+    //
 
     // The URL that this link will navigate to.
     DOMString url;
-  };
 
-  // Attributes which are mixed in to an AutomationNode if it is a document.
-  dictionary DocumentMixins {
+    //
+    // Document attributes.
+    //
+
     // The URL of this document.
     DOMString docUrl;
 
@@ -470,23 +393,22 @@
 
     // The proportion (out of 1.0) that this doc has completed loading.
     double docLoadingProgress;
-  };
 
-  // TODO(aboxhall): document ScrollableMixins (e.g. what is scrollXMin? is it
-  // ever not 0?)
+    //
+    // Scrollable container attributes.
+    //
 
-  // Attributes which are mixed in to an AutomationNode if it is scrollable.
-  dictionary ScrollableMixins {
     long scrollX;

[aboxhall, 2015/06/11 17:42:45]

One thing we were trying to avoid with mixins was the API explosion of having
every possible attribute exposed on every automation node, and having a long
list of attributes to parse at once in the documentation.

Is there any way we can keep this "mixin" style interface, but have it
implemented more efficiently?

[dmazzoni, 2015/06/11 19:09:12]

Rather than mixins, I think we could bundle attributes together in sub-objects.

For example, instead of node.scrollXMin, etc. you'd have node.scroll.xMin.

If you access node.scroll, it'd return an object if it has scrollable
interfaces, or undefined if it doesn't.

So you could write code like:

if (node.scroll) {
  outputScrollPosition(node.scroll.x, node.scroll.y);
}

Something like that sound good as a follow-up?

[aboxhall, 2015/06/11 22:22:34]

Sorry, missed this in my responses earlier.

Sure, something like this should work. As long as we have a solution to the two
problems I mentioned, I don't mind that much what it looks like. When do you
think you might get to that follow-up?

[dmazzoni, 2015/06/12 17:51:36]

I'll send out a proposal for just one set of attributes (former mixin) right
away, to follow this change.

     long scrollXMin;
     long scrollXMax;
     long scrollY;
     long scrollYMin;
     long scrollYMax;
-  };
 
-  // Attributes which are mixed in to an AutomationNode if it is editable text.
-  dictionary EditableTextMixins {
+    //
+    // Editable text field attributes.
+    //
+
     // The character index of the start of the selection within this editable
     // text element; -1 if no selection.
     long textSelStart;
@@ -497,10 +419,11 @@
 
     // The input type, like email or number.
     DOMString textInputType;
-  };
 
-  // Attributes which are mixed in to an AutomationNode if it is a range.
-  dictionary RangeMixins {
+    //
+    // Range attributes.
+    //
+
     // The current value for this range.
     double valueForRange;
 
@@ -509,21 +432,21 @@
 
     // The maximum possible value for this range.
     double maxValueForRange;
-  };
 
-  // TODO(aboxhall): live region mixins.
+    //
+    // Table attributes.
+    //
 
-  // Attributes which are mixed in to an AutomationNode if it is a table.
-  dictionary TableMixins {
     // The number of rows in this table.
     long tableRowCount;
 
     // The number of columns in this table.
     long tableColumnCount;
-  };
 
-  // Attributes which are mixed in to an AutomationNode if it is a table cell.
-  dictionary TableCellMixins {
+    //
+    // Table cell attributes.
+    //
+
     // The zero-based index of the column that this cell is in.
     long tableCellColumnIndex;
 
@@ -535,6 +458,75 @@
 
     // The number of rows that this cell spans (default is 1).
     long tableCellRowSpan;
+
+    //
+    // Walking the tree.
+    //
+
+    AutomationNode[] children;
+    AutomationNode parent;
+    AutomationNode firstChild;
+    AutomationNode lastChild;
+    AutomationNode previousSibling;
+    AutomationNode nextSibling;
+
+    // The index of this node in its parent node's list of children. If this is
+    // the root node, this will be undefined.
+    long? indexInParent;
+
+    //
+    // Actions.
+    //
+
+    // Does the default action based on this node's role. This is generally
+    // the same action that would result from clicking the node such as
+    // expanding a treeitem, toggling a checkbox, selecting a radiobutton,
+    // or activating a button.
+    static void doDefault();
+
+    // Places focus on this node.
+    static void focus();
+
+    // Scrolls this node to make it visible.
+    static void makeVisible();
+
+    // Sets selection within a text field.
+    static void setSelection(long startIndex, long endIndex);
+
+    // Adds a listener for the given event type and event phase.
+    static void addEventListener(
+        EventType eventType, AutomationListener listener, boolean capture);
+
+    // Removes a listener for the given event type and event phase.
+    static void removeEventListener(
+        EventType eventType, AutomationListener listener, boolean capture);
+
+    // Gets the first node in this node's subtree which matches the given CSS
+    // selector and is within the same DOM context.
+    //
+    // If this node doesn't correspond directly with an HTML node in the DOM,
+    // querySelector will be run on this node's nearest HTML node ancestor. Note
+    // that this may result in the query returning a node which is not a
+    // descendant of this node.
+    //
+    // If the selector matches a node which doesn't directly correspond to an
+    // automation node (for example an element within an ARIA widget, where the
+    // ARIA widget forms one node of the automation tree, or an element which
+    // is hidden from accessibility via hiding it using CSS or using
+    // aria-hidden), this will return the nearest ancestor which does correspond
+    // to an automation node.
+    static void domQuerySelector(DOMString selector, QueryCallback callback);
+
+    // Finds the first AutomationNode in this node's subtree which matches the
+    // given search parameters.
+    static AutomationNode find(FindParams params);
+
+    // Finds all the AutomationNodes in this node's subtree which matches the
+    // given search parameters.
+    static AutomationNode[] findAll(FindParams params);
+
+    // Returns whether this node matches the given $(ref:automation.FindParams).
+    static boolean matches(FindParams params);
   };
 
   // Called when the <code>AutomationNode</code> for the page is available.