Update touch selection to only modify one selection point at a time.

content/browser/web_contents/web_contents_impl.cc

 // 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.
 
 #include "content/browser/web_contents/web_contents_impl.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
@@ skipping 3193 matching lines @@
 
   // TODO(avi): Remove. http://crbug.com/170921
   int type = is_loading ? NOTIFICATION_LOAD_START : NOTIFICATION_LOAD_STOP;
   NotificationDetails det = NotificationService::NoDetails();
   if (details)
       det = Details<LoadNotificationDetails>(details);
   NotificationService::current()->Notify(
       type, Source<NavigationController>(&controller_), det);
 }
 
+void WebContentsImpl::MoveSelectionExtent(const gfx::Point& position) {
+  RenderFrameHost* focused_frame = GetFocusedFrame();
+  if (!focused_frame)
+    return;
+
+  focused_frame->Send(new InputMsg_MoveSelectionExtent(
+      focused_frame->GetRoutingID(), position));
+}
+
 void WebContentsImpl::SelectRange(const gfx::Point& start,
                                   const gfx::Point& end) {
   RenderFrameHost* focused_frame = GetFocusedFrame();
   if (!focused_frame)
     return;
 
   focused_frame->Send(
       new InputMsg_SelectRange(focused_frame->GetRoutingID(), start, end));
 }
 
@@ skipping 1147 matching lines @@
   node->render_manager()->ResumeResponseDeferredAtStart();
 }
 
 void WebContentsImpl::SetForceDisableOverscrollContent(bool force_disable) {
   force_disable_overscroll_content_ = force_disable;
   if (view_)
     view_->SetOverscrollControllerEnabled(CanOverscrollContent());
 }
 
 }  // namespace content