Refactor and send voice interaction structure

content/public/browser/web_contents.h

Index: content/public/browser/web_contents.h
diff --git a/content/public/browser/web_contents.h b/content/public/browser/web_contents.h
index f968ca22bcc00ec6ed8fbea79ba067f88e1963f7..ed6bf62905ce35862c62576d5914c89e3c380627 100644
--- a/content/public/browser/web_contents.h
+++ b/content/public/browser/web_contents.h
@@ -27,6 +27,7 @@
 #include "content/public/common/stop_find_action.h"
 #include "ipc/ipc_sender.h"
 #include "third_party/skia/include/core/SkColor.h"
+#include "ui/accessibility/ax_tree_update.h"
 #include "ui/base/window_open_disposition.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/native_widget_types.h"
@@ -278,6 +279,11 @@ class WebContents : public PageNavigator,
   // menus.
   virtual RenderWidgetHostView* GetTopLevelRenderWidgetHostView() = 0;
 
+  // Request a one-time snapshot of the accessibility tree without changing
+  // the accessibility mode.
+  using AXTreeSnapshotCallback = base::Callback<void(const ui::AXTreeUpdate&)>;
+  virtual void RequestAXTreeSnapshot(AXTreeSnapshotCallback callback) = 0;

[Luis Héctor Chávez, 2017/04/25 18:22:36]

does it make sense to have this be const AXTreeSnapshotCallback&? would doing
that prevent unnecessary copies?

[Muyuan, 2017/04/25 19:38:13]

The API originally looks like that.. gonna check with dmazzoni to see if we
should modify the API signature. 

[Muyuan, 2017/04/25 20:49:42]

After discussing with dmazzoni, it should be OK to change it to const
AXTreeSnapshotCallback&

+
   // Causes the current page to be closed, including running its onunload event
   // handler.
   virtual void ClosePage() = 0;