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

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index 3d8a05ffa6fc7c4d08920b9860da97b046ce2bdc..53190246c97196efbe5ebc5e1fb6e334e3e35d59 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -920,6 +920,8 @@ bool RenderFrameImpl::OnMessageReceived(const IPC::Message& msg) {
     IPC_MESSAGE_HANDLER(InputMsg_SelectAll, OnSelectAll)
     IPC_MESSAGE_HANDLER(InputMsg_SelectRange, OnSelectRange)
     IPC_MESSAGE_HANDLER(InputMsg_Unselect, OnUnselect)
+    IPC_MESSAGE_HANDLER(InputMsg_MoveRangeSelectionExtent,
+                        OnMoveRangeSelectionExtent)
     IPC_MESSAGE_HANDLER(InputMsg_Replace, OnReplace)
     IPC_MESSAGE_HANDLER(InputMsg_ReplaceMisspelling, OnReplaceMisspelling)
     IPC_MESSAGE_HANDLER(InputMsg_ExtendSelectionAndDelete,
@@ -1282,13 +1284,13 @@ void RenderFrameImpl::OnSelectAll() {
   frame_->executeCommand(WebString::fromUTF8("SelectAll"), GetFocusedElement());
 }
 
-void RenderFrameImpl::OnSelectRange(const gfx::Point& start,
-                                    const gfx::Point& end) {
+void RenderFrameImpl::OnSelectRange(const gfx::Point& base,
+                                    const gfx::Point& extent) {
   // This IPC is dispatched by RenderWidgetHost, so use its routing id.
-  Send(new ViewHostMsg_SelectRange_ACK(GetRenderWidget()->routing_id()));
+  Send(new InputHostMsg_SelectRange_ACK(GetRenderWidget()->routing_id()));
 
   base::AutoReset<bool> handling_select_range(&handling_select_range_, true);
-  frame_->selectRange(start, end);
+  frame_->selectRange(base, extent);
 }
 
 void RenderFrameImpl::OnUnselect() {
@@ -1296,6 +1298,15 @@ void RenderFrameImpl::OnUnselect() {
   frame_->executeCommand(WebString::fromUTF8("Unselect"), GetFocusedElement());
 }
 
+void RenderFrameImpl::OnMoveRangeSelectionExtent(const gfx::Point& point) {
+  // This IPC is dispatched by RenderWidgetHost, so use its routing id.
+  Send(new InputHostMsg_MoveRangeSelectionExtent_ACK(
+      GetRenderWidget()->routing_id()));
+
+  base::AutoReset<bool> handling_select_range(&handling_select_range_, true);
+  frame_->moveRangeSelectionExtent(point);
+}
+
 void RenderFrameImpl::OnReplace(const base::string16& text) {
   if (!frame_->hasSelection())
     frame_->selectWordAroundCaret();