Add a WebContentsImpl API to snapshot the accessibility tree.

content/browser/web_contents/web_contents_impl.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 186 matching lines @@
   // Adds the given accessibility mode to the current accessibility mode
   // bitmap.
   void AddAccessibilityMode(AccessibilityMode mode);
 
   // Removes the given accessibility mode from the current accessibility
   // mode bitmap, managing the bits that are shared with other modes such
   // that a bit will only be turned off when all modes that depend on it
   // have been removed.
   void RemoveAccessibilityMode(AccessibilityMode mode);
 
+  // Request a one-time snapshot of the accessibility tree without changing
+  // the accessibility mode.
+  typedef base::Callback<void(const ui::AXTreeUpdate&)>
+      AXTreeSnapshotCallback;
+  void RequestAXTreeSnapshot(AXTreeSnapshotCallback callback);
+
   // Clear the navigation transition data when the user navigates back to Chrome
   // from a native app.
   void ClearNavigationTransitionData();
 
   // WebContents ------------------------------------------------------
   WebContentsDelegate* GetDelegate() override;
   void SetDelegate(WebContentsDelegate* delegate) override;
   NavigationControllerImpl& GetController() override;
   const NavigationControllerImpl& GetController() const override;
   BrowserContext* GetBrowserContext() const override;
@@ skipping 1061 matching lines @@
   // Adds/removes a callback called on creation of each new WebContents.
   static void AddCreatedCallbackForTesting(const CreatedCallback& callback);
   static void RemoveCreatedCallbackForTesting(const CreatedCallback& callback);
 
   DISALLOW_COPY_AND_ASSIGN(FriendZone);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_