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

content/common/accessibility_messages.h

Index: content/common/accessibility_messages.h
diff --git a/content/common/accessibility_messages.h b/content/common/accessibility_messages.h
index 1830a1b4d172f4486d7b7eee9e039c1863fdaca7..3a9ccb7ee3acd52b67bb4ee40cd997068c6328ea 100644
--- a/content/common/accessibility_messages.h
+++ b/content/common/accessibility_messages.h
@@ -105,11 +105,15 @@ IPC_MESSAGE_ROUTED3(AccessibilityMsg_SetTextSelection,
                     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)