Views: don't unnecessarily create temp label when sizing LocationIconView

This change is a 15% resize speedup in a release build on my machine.

Bug: 850128
Change-Id: Icbcd79b7ea5a8a5f06fc20595f67092b8bd12c42
Reviewed-on: https://chromium-review.googlesource.com/1110700Reviewed-by: Tommy Li <tommycli@chromium.org>
Reviewed-by: Robert Liao <robliao@chromium.org>
Commit-Queue: Leonard Grey <lgrey@chromium.org>
Cr-Commit-Position: refs/heads/master@{#570903}

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

@@ -104,9 +104,17 @@ bool LocationIconView::IsBubbleShowing() const {
 
 gfx::Size LocationIconView::GetMinimumSizeForLabelText(
     const base::string16& text) const {
-  views::Label label(text, {font_list()});
-  return GetMinimumSizeForPreferredSize(
-      GetSizeForLabelWidth(label.GetPreferredSize().width()));
+  int width = 0;
+  if (text == label()->text()) {
+    // Optimize this common case by not creating a new label.
+    // GetPreferredSize is not dependent on the label's current
+    // width, so this returns the same value as the branch below.
+    width = label()->GetPreferredSize().width();
+  } else {
+    views::Label label(text, {font_list()});
+    width = label.GetPreferredSize().width();
+  }
+  return GetMinimumSizeForPreferredSize(GetSizeForLabelWidth(width));
 }
 
 void LocationIconView::SetTextVisibility(bool should_show,