Add support for Quick Menu with Smart Text Selection actions

Implements TouchSelectionMenuClient functions required to request Smart
Text Selection actions and to open the Quick Menu on cross-process
subframes.

Bug: 1020334
Change-Id: Iba3e6139db266a3ed1ea5dfbbf49c83ea7d5f3b1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1954405Reviewed-by: David Jacobo <djacobo@chromium.org>
Reviewed-by: Timothy Dresser <tdresser@chromium.org>
Commit-Queue: Jorge Gil <jorgegil@google.com>
Auto-Submit: Jorge Gil <jorgegil@google.com>
Cr-Commit-Position: refs/heads/master@{#723553}

content/browser/renderer_host/input/touch_selection_controller_client_child_frame.cc

@@ -199,13 +199,11 @@ void TouchSelectionControllerClientChildFrame::RunContextMenu() {
 }
 
 bool TouchSelectionControllerClientChildFrame::ShouldShowQuickMenu() {
-  NOTREACHED();
-  return false;
+  return true;
 }
 
 base::string16 TouchSelectionControllerClientChildFrame::GetSelectedText() {
-  NOTREACHED();
-  return base::string16();
+  return rwhv_->GetSelectedText();
 }
 
 }  // namespace content