Remove confusing comment from KeywordHintView::SetKeyword

This comment should have been removed with code review 1211963
because the bug fixed there was precisely the change of color
depending on popup state.

Bug: 879935
Change-Id: Ie4dd596a96050759d45bd542a75ab06e066c3797
Reviewed-on: https://chromium-review.googlesource.com/1240203Reviewed-by: Justin Donnelly <jdonnelly@chromium.org>
Commit-Queue: Orin Jaworski <orinj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593664}

chrome/browser/ui/views/location_bar/keyword_hint_view.cc

@@ -93,8 +93,6 @@ KeywordHintView::~KeywordHintView() {}
 
 void KeywordHintView::SetKeyword(const base::string16& keyword,
                                  SkColor background_color) {
-  // In the newer MD style, the KeywordHintView chip background should match the
-  // LocationBarView's background, which changes when the popup is open.
   if (ui::MaterialDesignController::IsNewerMaterialUi()) {
     chip_label_->SetBackgroundColor(background_color);
     chip_container_->background()->SetNativeControlColor(background_color);