Delete some unused code found by the clang static analyzer.

chrome/browser/ui/cocoa/browser_window_controller_private.mm

Index: chrome/browser/ui/cocoa/browser_window_controller_private.mm
diff --git a/chrome/browser/ui/cocoa/browser_window_controller_private.mm b/chrome/browser/ui/cocoa/browser_window_controller_private.mm
index c63bc0b9af2db2feb04a6deb5baa0a20bce8d5aa..cdd590ef435d982a83b93e876c098c418590bb2e 100644
--- a/chrome/browser/ui/cocoa/browser_window_controller_private.mm
+++ b/chrome/browser/ui/cocoa/browser_window_controller_private.mm
@@ -215,7 +215,6 @@ willPositionSheet:(NSWindow*)sheet
       (std::floor((1 - floatingBarShownFraction_) * floatingBarHeight) -
           [presentationModeController_ floatingBarVerticalOffset]) : 0;
   CGFloat maxY = NSMaxY(contentBounds) + yOffset;
-  CGFloat startMaxY = maxY;
 
   CGFloat overlayMaxY =
       NSMaxY([window frame]) +
@@ -224,10 +223,8 @@ willPositionSheet:(NSWindow*)sheet
                                       overlayMaxY:overlayMaxY];
 
   if ([self hasTabStrip]) {
-    // If we need to lay out the top tab strip, replace |maxY| and |startMaxY|
-    // with higher values, and then lay out the tab strip.
-    NSRect windowFrame = [contentView convertRect:[window frame] fromView:nil];
-    startMaxY = maxY = NSHeight(windowFrame) + yOffset;
+    // If we need to lay out the top tab strip, replace |maxY| with a higher
+    // value, and then lay out the tab strip.
     maxY = [self layoutTabStripAtMaxY:maxY
                                 width:width
                            fullscreen:[self isFullscreen]];