Implement Android accessible hit testing using an IPC to the renderer process.

content/common/accessibility_messages.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.
 
 // IPC messages for accessibility.
 // Multiply-included message file, hence no include guard.
 
 #include "base/basictypes.h"
 #include "content/common/content_export.h"
 #include "content/common/view_message_enums.h"
@@ skipping 87 matching lines @@
                     int /* object id */,
                     gfx::Point /* new location */)
 
 // Relay a request from assistive technology to set the cursor or
 // selection within an editable text element.
 IPC_MESSAGE_ROUTED3(AccessibilityMsg_SetTextSelection,
                     int /* object id */,
                     int /* New start offset */,
                     int /* New end offset */)
 
+// Determine the accessibility object under a given point and reply with
+// a AccessibilityHostMsg_HitTestResult with the same id.
+IPC_MESSAGE_ROUTED1(AccessibilityMsg_HitTest,
+                    gfx::Point /* location to test */);
+
 // Tells the render view that a AccessibilityHostMsg_Events
 // message was processed and it can send addition events.
 IPC_MESSAGE_ROUTED0(AccessibilityMsg_Events_ACK)
 
 
 // Kill the renderer because we got a fatal error in the accessibility tree.
 IPC_MESSAGE_ROUTED0(AccessibilityMsg_FatalError)
 
 // Messages sent from the renderer to the browser.
 
 // Sent to notify the browser about renderer accessibility events.
 // The browser responds with a AccessibilityMsg_Events_ACK.
 IPC_MESSAGE_ROUTED1(
     AccessibilityHostMsg_Events,
     std::vector<AccessibilityHostMsg_EventParams>)
 
 // Sent to update the browser of the location of accessibility objects.
 IPC_MESSAGE_ROUTED1(
     AccessibilityHostMsg_LocationChanges,
     std::vector<AccessibilityHostMsg_LocationChangeParams>)