Use text affinity to return correct accessible line boundaries.

chrome/common/extensions/chrome_extension_messages.h

 // Copyright 2014 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.
 
 // Chrome-specific IPC messages for extensions.
 // Extension-related messages that aren't specific to Chrome live in
 // extensions/common/extension_messages.h.
 //
 // Multiply-included message file, hence no include guard.
 
@@ skipping 68 matching lines @@
   IPC_STRUCT_TRAITS_MEMBER(focused_tree_id)
   IPC_STRUCT_TRAITS_MEMBER(url)
   IPC_STRUCT_TRAITS_MEMBER(title)
   IPC_STRUCT_TRAITS_MEMBER(mimetype)
   IPC_STRUCT_TRAITS_MEMBER(doctype)
   IPC_STRUCT_TRAITS_MEMBER(loaded)
   IPC_STRUCT_TRAITS_MEMBER(loading_progress)
   IPC_STRUCT_TRAITS_MEMBER(focus_id)
   IPC_STRUCT_TRAITS_MEMBER(sel_anchor_object_id)
   IPC_STRUCT_TRAITS_MEMBER(sel_anchor_offset)
+  IPC_STRUCT_TRAITS_MEMBER(sel_anchor_affinity)
   IPC_STRUCT_TRAITS_MEMBER(sel_focus_object_id)
   IPC_STRUCT_TRAITS_MEMBER(sel_focus_offset)
+  IPC_STRUCT_TRAITS_MEMBER(sel_focus_affinity)
 IPC_STRUCT_TRAITS_END()
 
 IPC_STRUCT_TRAITS_BEGIN(ui::AXTreeUpdate)
   IPC_STRUCT_TRAITS_MEMBER(has_tree_data)
   IPC_STRUCT_TRAITS_MEMBER(tree_data)
   IPC_STRUCT_TRAITS_MEMBER(node_id_to_clear)
   IPC_STRUCT_TRAITS_MEMBER(root_id)
   IPC_STRUCT_TRAITS_MEMBER(nodes)
 IPC_STRUCT_TRAITS_END()
 
@@ skipping 23 matching lines @@
 // Messages sent from the renderer to the browser.
 
 
 // Sent by the renderer to implement chrome.webstore.install().
 IPC_MESSAGE_ROUTED5(ExtensionHostMsg_InlineWebstoreInstall,
                     int32_t /* install id */,
                     int32_t /* return route id */,
                     std::string /* Web Store item ID */,
                     GURL /* requestor URL */,
                     int /* listeners_mask */)