Bug 1390448 - Restore vertical margin calculation in browser-tabsintitlebar.js, add 1px to window control margin on Windows 10. r=dao

MozReview-Commit-ID: LXR2zrAZS0k

--HG--
extra : rebase_source : 807e7c6da20958261b4da2a79b36a9e710931af1

browser/base/content/browser-tabsintitlebar.js

@@ -160,7 +160,9 @@ var TabsInTitlebar = {
       // then later set the properties affecting layout together in a batch.
 
       // Get the height of the tabs toolbar:
-      let tabsHeight = rect($("TabsToolbar")).height;
+      let tabsToolbar = $("TabsToolbar");
+      let tabsStyles = window.getComputedStyle(tabsToolbar);
+      let fullTabsHeight = rect($("TabsToolbar")).height + verticalMargins(tabsStyles);
       // Buttons first:
       let captionButtonsBoxWidth = rect($("titlebar-buttonbox-container")).width;
 
@@ -186,7 +188,8 @@ var TabsInTitlebar = {
       // tab strip height if we're not showing a menu bar.
       if (AppConstants.isPlatformAndVersionAtLeast("win", "10.0")) {
         if (!menuHeight) {
-          titlebarContentHeight = tabsHeight;
+          // Add a pixel to slightly overlap the navbar border.
+          titlebarContentHeight = fullTabsHeight + 1;
           $("titlebar-buttonbox").style.height = titlebarContentHeight + "px";
         }
       }
@@ -220,7 +223,7 @@ var TabsInTitlebar = {
 
       // Next, we calculate how much we need to stretch the titlebar down to
       // go all the way to the bottom of the tab strip, if necessary.
-      let tabAndMenuHeight = tabsHeight + fullMenuHeight;
+      let tabAndMenuHeight = fullTabsHeight + fullMenuHeight;
 
       if (tabAndMenuHeight > titlebarContentHeight) {
         // We need to increase the titlebar content's outer height (ie including margins)

browser/base/content/test/performance/browser_windowopen_reflows.js

@@ -80,6 +80,16 @@ if (Services.appinfo.OS == "WINNT") {
 
 if (Services.appinfo.OS == "WINNT" || Services.appinfo.OS == "Darwin") {
   EXPECTED_REFLOWS.push(
+    {
+      stack: [
+        "verticalMargins@chrome://browser/content/browser-tabsintitlebar.js",
+        "_update@chrome://browser/content/browser-tabsintitlebar.js",
+        "init@chrome://browser/content/browser-tabsintitlebar.js",
+        "handleEvent@chrome://browser/content/tabbrowser.xml",
+      ],
+      times: 2, // This number should only ever go down - never up.
+    },
+
     {
       stack: [
         "rect@chrome://browser/content/browser-tabsintitlebar.js",