Changed kBottomMargin of the detached bookmark bar from 4 to 2 pixels.

This makes the detached bookmarks items vertically centered.

Bug: 863697
Change-Id: Icf6529ec0b33255dc8072d5bfacc2f32b0495f93
Reviewed-on: https://chromium-review.googlesource.com/1139191Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Commit-Queue: Charlene Yan <cyan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575746}

chrome/browser/ui/views/bookmarks/bookmark_bar_view.cc

@@ -128,7 +128,7 @@ static const int kMaxButtonWidth = 150;
 // Margins around the content.
 static const int kDetachedTopMargin = 1;  // When attached, we use 0 and let the
                                           // toolbar above serve as the margin.
-static const int kBottomMargin = 4;
+static const int kBottomMargin = 2;
 static const int kHorizontalMargin = 8;
 
 // Padding between buttons.