Adds selection expansion support for Contextual Search.

content/common/view_messages.h

Index: content/common/view_messages.h
diff --git a/content/common/view_messages.h b/content/common/view_messages.h
index fcacbce4a1dcfc1f65205bb6db7b5c0ccdbcf405..3b256fa8ef81e2a1f368a31eb366afd04d57a9f5 100644
--- a/content/common/view_messages.h
+++ b/content/common/view_messages.h
@@ -991,6 +991,12 @@ IPC_MESSAGE_ROUTED1(ViewMsg_SetSurfaceIdNamespace,
 
 IPC_MESSAGE_ROUTED0(ViewMsg_SelectWordAroundCaret)
 
+// Sent by the browser to ask the renderer to expand the selection
+// by the given amounts.
+IPC_MESSAGE_ROUTED2(ViewMsg_ExpandSelectionByCharacterOffset,
+                    int /* start_adjust*/,
+                    int /* end_adjust */)
+
 // Sent by the browser to ask the renderer to redraw.
 // If |request_id| is not zero, it is added to the forced frame's latency info
 // as ui::WINDOW_SNAPSHOT_FRAME_NUMBER_COMPONENT.