Speculative Fix for a crash report-BookmarkBarView::ButtonPressed

https://codereview.chromium.org/2946813002 was intended to fix a issue
when |contents| is null and bookmark bar exists. But it also
unintendedly changed case when when |contents| is null and bookmark
bar does not exist. This patch just reverts that case.

The crash is not easily reproducible. This CL only speculatively fix
the crash. The bug will remain open until the crash is confirmed fix.

BUG=744211

Change-Id: Id092d16a75e087650a7edcba27115809de446d57
Reviewed-on: https://chromium-review.googlesource.com/595250
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491867}

chrome/browser/ui/views/frame/browser_view.cc

@@ -2220,7 +2220,7 @@ ContentsLayoutManager* BrowserView::GetContentsLayoutManager() const {
 bool BrowserView::MaybeShowBookmarkBar(WebContents* contents) {
   bool show_bookmark_bar =
       browser_->SupportsWindowFeature(Browser::FEATURE_BOOKMARKBAR);
-  if (!show_bookmark_bar && !bookmark_bar_view_.get())
+  if ((!show_bookmark_bar || !contents) && !bookmark_bar_view_.get())
     return false;
   if (!bookmark_bar_view_.get()) {
     bookmark_bar_view_.reset(new BookmarkBarView(browser_.get(), this));