refactor: remove 10.9 specific window conditions

atom/browser/native_window_mac.mm

@@ -1359,23 +1359,6 @@ void ViewDidMoveToSuperview(NSView* self, SEL _cmd) {
 }
 
 void NativeWindowMac::AddContentViewLayers() {
-  // Make sure the bottom corner is rounded for non-modal windows:
-  // http://crbug.com/396264. But do not enable it on OS X 10.9 for transparent
-  // window, otherwise a semi-transparent frame would show.
-  if (!(transparent() && base::mac::IsOS10_9()) && !is_modal()) {
-    // For normal window, we need to explicitly set layer for contentView to
-    // make setBackgroundColor work correctly.
-    // There is no need to do so for frameless window, and doing so would make
-    // titleBarStyle stop working.
-    if (has_frame()) {
-      base::scoped_nsobject<CALayer> background_layer([[CALayer alloc] init]);
-      [background_layer
-          setAutoresizingMask:kCALayerWidthSizable | kCALayerHeightSizable];
-      [[window_ contentView] setLayer:background_layer];
-    }
-    [[window_ contentView] setWantsLayer:YES];
-  }
-
   if (!has_frame()) {
     // In OSX 10.10, adding subviews to the root view for the NSView hierarchy
     // produces warnings. To eliminate the warnings, we resize the contentView
@@ -1399,15 +1382,6 @@ void ViewDidMoveToSuperview(NSView* self, SEL _cmd) {
           [[CustomWindowButtonView alloc] initWithFrame:NSZeroRect]);
       [[window_ contentView] addSubview:buttons_view_];
     } else {
-      if (title_bar_style_ != NORMAL) {
-        if (base::mac::IsOS10_9()) {
-          ShowWindowButton(NSWindowZoomButton);
-          ShowWindowButton(NSWindowMiniaturizeButton);
-          ShowWindowButton(NSWindowCloseButton);
-        }
-        return;
-      }
-
       // Hide the window buttons.
       [[window_ standardWindowButton:NSWindowZoomButton] setHidden:YES];
       [[window_ standardWindowButton:NSWindowMiniaturizeButton] setHidden:YES];