[vr] Disable text suggestions in immersive mode

This feature is not currently supported, though we hope to add support
soon. This work is tracked in crbug.com/779126

Bug: 818012
Change-Id: Ib677f7ea62b9f681ba494c27367b286a122dd10f
Reviewed-on: https://chromium-review.googlesource.com/944543
Commit-Queue: Ian Vollick <vollick@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541461}

third_party/WebKit/Source/core/editing/suggestion/TextSuggestionController.cpp

@@ -19,6 +19,7 @@
 #include "core/editing/suggestion/TextSuggestionInfo.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
+#include "core/frame/Settings.h"
 #include "core/layout/LayoutTheme.h"
 #include "services/service_manager/public/cpp/interface_provider.h"
 
@@ -206,6 +207,10 @@ bool TextSuggestionController::IsMenuOpen() const {
 
 void TextSuggestionController::HandlePotentialSuggestionTap(
     const PositionInFlatTree& caret_position) {
+  // TODO(crbug.com/779126): add support for suggestions in immersive mode.
+  if (GetDocument().GetSettings()->GetImmersiveModeEnabled())
+    return;
+
   // It's theoretically possible, but extremely unlikely, that the user has
   // managed to tap on some text after TextSuggestionController has told the
   // browser to open the text suggestions menu, but before the browser has