Initial support for native accessibility in ARC

components/arc/common/accessibility_helper.mojom

Index: components/arc/common/accessibility_helper.mojom
diff --git a/components/arc/common/accessibility_helper.mojom b/components/arc/common/accessibility_helper.mojom
index 325006dc5e6742dacd62fa609ca492efaec83812..5b465814751bb1f43afd3f53ae1f2d15bf3e9a4a 100644
--- a/components/arc/common/accessibility_helper.mojom
+++ b/components/arc/common/accessibility_helper.mojom
@@ -8,12 +8,90 @@ module arc.mojom;
 
 import "screen_rect.mojom";
 
-// AccessibilityEventType is a enum which corresponds to event types of
-// AccessibilityEvent in Android.
+// AccessibilityEventType lists the possible accessibility events on Android.
 // https://developer.android.com/reference/android/view/accessibility/AccessibilityEvent.html
 [Extensible]
 enum AccessibilityEventType {
   VIEW_FOCUSED,
+  VIEW_SELECTED,
+  VIEW_CLICKED,
+  VIEW_LONG_CLICKED,
+  VIEW_TEXT_CHANGED,
+  WINDOW_STATE_CHANGED,

[dmazzoni, 2017/02/09 01:18:09]

Are these supposed to match the order of Android events?

If so, document them, otherwise please sort them.

+  NOTIFICATION_STATE_CHANGED,
+  VIEW_HOVER_ENTER,
+  VIEW_HOVER_EXIT,
+  TOUCH_EXPLORATION_GESTURE_START,
+  TOUCH_EXPLORATION_GESTURE_END,
+  WINDOW_CONTENT_CHANGED,
+  VIEW_SCROLLED,
+  VIEW_TEXT_SELECTION_CHANGED,
+  ANNOUNCEMENT,
+  VIEW_ACCESSIBILITY_FOCUSED,
+  VIEW_ACCESSIBILITY_FOCUS_CLEARED,
+  VIEW_TEXT_TRAVERSED_AT_MOVEMENT_GRANULARITY,
+  GESTURE_DETECTION_START,
+  GESTURE_DETECTION_END,
+  TOUCH_INTERACTION_START,
+  TOUCH_INTERACTION_END,
+  WINDOWS_CHANGED,
+  VIEW_CONTEXT_CLICKED,
+  ASSIST_READING_CONTEXT,
+};
+
+// AccessibilityActionType lists possible accessibility actions on Android.
+// https://developer.android.com/reference/android/view/accessibility/AccessibilityNodeInfo.html
+// Please note the omission of

[dmazzoni, 2017/02/09 01:18:09]

Might be simpler to just map all of them even if some are unused.

+//    NEXT_AT_MOVEMENT_GRANULARITY,
+//    PREVIOUS_AT_MOVEMENT_GRANULARITY,
+//    NEXT_HTML_ELEMENT,
+//    PREVIOUS_HTML_ELEMENT
+// Also note the omission of argument type mappings e.g. for setting selection.
+[Extensible]
+enum AccessibilityActionType {
+  FOCUS,
+  CLEAR_FOCUS,
+  SELECT,
+  CLEAR_SELECTION,
+  CLICK,
+  LONG_CLICK,
+  ACCESSIBILITY_FOCUS,
+  CLEAR_ACCESSIBILITY_FOCUS,
+  SCROLL_FORWARD,
+  SCROLL_BACKWARD,
+COPY,

[dmazzoni, 2017/02/09 01:18:09]

nit: some of these need indentation.

Also, please sort all

+  PASTE,
+  CUT,
+SET_SELECTION,
+  EXPAND,
+  COLLAPSE,
+DISMISS,
+  SET_TEXT
+};
+
+// Possible boolean properties set on an AccessibilityNodeInfo.
+// https://developer.android.com/reference/android/view/accessibility/AccessibilityNodeInfo.html
+[Extensible]
+enum AccessibilityBooleanProperty {
+  CHECKABLE,

[dmazzoni, 2017/02/09 01:18:09]

sort

+  CHECKED,
+  FOCUSABLE,
+  FOCUSED,
+  SELECTED,
+  CLICKABLE,
+  LONG_CLICKABLE,
+  ENABLED,
+  PASSWORD,
+  SCROLLABLE,
+  ACCESSIBILITY_FOCUSED,
+  VISIBLE_TO_USER,
+  EDITABLE,
+  OPENS_POPUP,
+  DISMISSABLE,
+  MULTI_LINE,
+  CONTENT_INVALID,
+  CONTEXT_CLICKABLE,
+  IMPORTANCE
 };
 
 // AccessibilityNodeInfoData is a struct to contain info of
@@ -21,17 +99,49 @@ enum AccessibilityEventType {
 // https://developer.android.com/reference/android/view/accessibility/AccessibilityNodeInfo.html
 struct AccessibilityNodeInfoData {
   ScreenRect boundsInScreen;
+  int32 id;

[yawano, 2017/02/09 10:55:30]

I think this will correspond to AccessibilityNodeInfo.getViewIdResourceName().
Would this be string?

+  string contentDescription;

[dmazzoni, 2017/02/09 01:18:09]

how about map<> stringProperties?

[yawano, 2017/02/09 10:55:30]

+1 for map<AccessibilityStringProperty> as it will make it easier to add or
remove fields of this field later.

+  string text;
+  string className;
+  map<AccessibilityBooleanProperty, bool> booleanProperties;
+  array<int32> childIds;

[yawano, 2017/02/09 10:55:30]

Add [MinVersion=1] to the new fields to keep backward compatibility.

+};
+
+// Filters the event type (and implicitly the data) sent by the ARC accessibility service.
+enum AccessibilityFilterType {

[yawano, 2017/02/09 10:55:30]

Mark this [Extensible] as we can extend this later.

+  // No events will be sent.
+  OFF,
+
+  // Only send focus events along with the source focus node.
+  FOCUS,
+
+// Send a complete tree from the event source's root for every event.

[dmazzoni, 2017/02/09 01:18:09]

nit: indent

+  ALL
+};
+
+// AccessibilityEventData is a struct to contain info of
+// AccessibilityEvent in Android.
+// https://developer.android.com/reference/android/view/accessibility/AccessibilityEvent.html
+struct AccessibilityEventData {
+  AccessibilityEventType eventType;
+  int32 sourceId;
+  array<AccessibilityNodeInfoData> nodeData;
 };
 
 // Next method ID: 1
 interface AccessibilityHelperHost {
   // OnAccessibilityEvent is called when a converted Android accessibility event
   // is sent from Android.
-  OnAccessibilityEvent@0(AccessibilityEventType eventType,
-                         AccessibilityNodeInfoData? eventSource);
+  OnAccessibilityEvent@0(AccessibilityEventData eventData);

[yawano, 2017/02/09 10:55:30]

We cannot simply change the arguments of existing method. You need to do the
following things.

1. Deprecate the current method. Rename OnAccessibilityEvent@0 to
OnAccessibilityEventDeperecated@0.
2. Add new method with the new interface. Add OnAccessibilityEvent@1.
3. Keep the OnAccessibilityEventDeperecated@0 work correctly. Simply proxying to
the new interface is okay.

GetFileSizeDeprecated in intent_helper.mojom will be an example.
https://cs.chromium.org/chromium/src/components/arc/common/intent_helper.mojo...

 };
 
-// Next method ID: 1
+// Next method ID: 3
 interface AccessibilityHelperInstance {
   Init@0(AccessibilityHelperHost host);
+
+  // Perform the specified action on a node requested by a Chrome client.
+  PerformAction@1(int32 id, AccessibilityActionType action);
+
+  // Set a filter on the event types received.
+  SetFilter@2(AccessibilityFilterType filterType);
 };