Reland: Implement Aura side of unified touch text selection for contents

content/browser/renderer_host/input/touch_selection_controller.cc

Index: content/browser/renderer_host/input/touch_selection_controller.cc
diff --git a/content/browser/renderer_host/input/touch_selection_controller.cc b/content/browser/renderer_host/input/touch_selection_controller.cc
index e904e283ee0716401cea8556353b8eba048032d1..7354703bacc6ceb78c430e46653f132b62dbea3a 100644
--- a/content/browser/renderer_host/input/touch_selection_controller.cc
+++ b/content/browser/renderer_host/input/touch_selection_controller.cc
@@ -46,7 +46,7 @@ TouchSelectionController::TouchSelectionController(
       selection_editable_(false),
       temporarily_hidden_(false) {
   DCHECK(client_);
-  HideAndDisallowShowingAutomatically();
+  HideAndDisallowShowingAutomatically(); // XXX: needed?
 }
 
 TouchSelectionController::~TouchSelectionController() {
@@ -203,6 +203,15 @@ bool TouchSelectionController::Animate(base::TimeTicks frame_time) {
   return false;
 }
 
+void TouchSelectionController::ActivateSelection(
+    const cc::ViewportSelectionBound& start,
+    const cc::ViewportSelectionBound& end) {
+  if (start.edge_bottom != end.edge_bottom) {
+    ShowSelectionHandlesAutomatically();
+    OnSelectionBoundsChanged(start, end);
+  }
+}
+
 void TouchSelectionController::OnHandleDragBegin(const TouchHandle& handle) {
   if (&handle == insertion_handle_.get()) {
     client_->OnSelectionEvent(INSERTION_DRAG_STARTED, handle.position());
@@ -300,7 +309,7 @@ void TouchSelectionController::OnInsertionChanged() {
 void TouchSelectionController::OnSelectionChanged() {
   DeactivateInsertion();
 
-  if (!activate_selection_automatically_)
+  if (!activate_selection_automatically_) // XXX: needed?
     return;
 
   const bool was_active = is_selection_active_;