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

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index c17dcf3fad339798ec5d8e6b266121d7b0ef2015..d3e8b13b9d3dbba81e04229caf1ad69f00cf4940 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -3174,14 +3174,23 @@ void WebContentsImpl::SetIsLoading(RenderViewHost* render_view_host,
       type, Source<NavigationController>(&controller_), det);
 }
 
-void WebContentsImpl::SelectRange(const gfx::Point& start,
-                                  const gfx::Point& end) {
+void WebContentsImpl::MoveRangeSelectionExtent(const gfx::Point& extent) {
+  RenderFrameHost* focused_frame = GetFocusedFrame();
+  if (!focused_frame)
+    return;
+
+  focused_frame->Send(new InputMsg_MoveRangeSelectionExtent(
+      focused_frame->GetRoutingID(), extent));
+}
+
+void WebContentsImpl::SelectRange(const gfx::Point& base,
+                                  const gfx::Point& extent) {
   RenderFrameHost* focused_frame = GetFocusedFrame();
   if (!focused_frame)
     return;
 
   focused_frame->Send(
-      new InputMsg_SelectRange(focused_frame->GetRoutingID(), start, end));
+      new InputMsg_SelectRange(focused_frame->GetRoutingID(), base, extent));
 }
 
 void WebContentsImpl::UpdateMaxPageIDIfNecessary(RenderViewHost* rvh) {