Fix Views Textfield drag selection behavior past edges.

ui/views/controls/textfield/textfield.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 "ui/views/controls/textfield/textfield.h"
 
 #include <string>
 
 #include "base/trace_event/trace_event.h"
 #include "ui/accessibility/ax_view_state.h"
@@ skipping 629 matching lines @@
   last_drag_location_ = event.location();
 
   // Don't adjust the cursor on a potential drag and drop, or if the mouse
   // movement from the last mouse click does not exceed the drag threshold.
   if (initiating_drag_ || !event.IsOnlyLeftMouseButton() ||
       !ExceededDragThreshold(last_drag_location_ - last_click_location_)) {
     return true;
   }
 
   // A timer is used to continuously scroll while selecting beyond side edges.
-  if ((event.location().x() > 0 && event.location().x() < size().width()) ||
-      GetDragSelectionDelay() == 0) {
+  const int x = event.location().x();
+  if ((x >= 0 && x <= width()) || GetDragSelectionDelay() == 0) {
     drag_selection_timer_.Stop();
     SelectThroughLastDragLocation();
   } else if (!drag_selection_timer_.IsRunning()) {
+    // Select through the edge of the visible text, then start the scroll timer.
+    last_drag_location_.set_x(std::min(std::max(0, x), width()));
+    SelectThroughLastDragLocation();
     drag_selection_timer_.Start(
         FROM_HERE, base::TimeDelta::FromMilliseconds(GetDragSelectionDelay()),
         this, &Textfield::SelectThroughLastDragLocation);
   }
 
   return true;
 }
 
 void Textfield::OnMouseReleased(const ui::MouseEvent& event) {
   OnBeforeUserAction();
@@ skipping 1222 matching lines @@
     RequestFocus();
   model_->MoveCursorTo(mouse);
   if (!selection_clipboard_text.empty()) {
     model_->InsertText(selection_clipboard_text);
     UpdateAfterChange(true, true);
   }
   OnAfterUserAction();
 }
 
 }  // namespace views