Add always-on-top property to app windows

chrome/browser/ui/cocoa/apps/native_app_window_cocoa.mm

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/cocoa/apps/native_app_window_cocoa.h"
 
 #include "apps/app_shim/extension_app_shim_handler_mac.h"
 #include "base/command_line.h"
 #include "base/mac/mac_util.h"
 #include "base/strings/sys_string_conversions.h"
@@ skipping 247 matching lines @@
 - (void)mouseDragged:(NSEvent*)event {
   appWindow_->HandleMouseEvent(event);
 }
 
 @end
 
 @interface NSView (WebContentsView)
 - (void)setMouseDownCanMoveWindow:(BOOL)can_move;
 @end
 
+namespace {
+
+const NSInteger kAlwaysOnTopWindowLevel = NSFloatingWindowLevel;
+
+}  // namespace
+
 NativeAppWindowCocoa::NativeAppWindowCocoa(
     ShellWindow* shell_window,
     const ShellWindow::CreateParams& params)
     : shell_window_(shell_window),
       has_frame_(params.frame == ShellWindow::FRAME_CHROME),
       is_hidden_(false),
       is_hidden_with_app_(false),
       is_maximized_(false),
       is_fullscreen_(false),
       attention_request_id_(0),
@@ skipping 49 matching lines @@
   if (IsBoundedSize(max_size_)) {
     CGFloat max_width = max_size_.width() ? max_size_.width() : CGFLOAT_MAX;
     CGFloat max_height = max_size_.height() ? max_size_.height() : CGFLOAT_MAX;
     [window setContentMaxSize:NSMakeSize(max_width, max_height)];
   }
 
   if (base::mac::IsOSSnowLeopard() &&
       [window respondsToSelector:@selector(setBottomCornerRounded:)])
     [window setBottomCornerRounded:NO];
 
+  if (params.always_on_top)
+    [window setLevel:kAlwaysOnTopWindowLevel];
+
   // Set the window to participate in Lion Fullscreen mode. Setting this flag
   // has no effect on Snow Leopard or earlier. UI controls for fullscreen are
   // only shown for apps that have unbounded size.
   if (shows_fullscreen_controls_)
     SetFullScreenCollectionBehavior(window, true);
 
   window_controller_.reset(
       [[NativeAppWindowController alloc] initWithWindow:window.release()]);
 
   NSView* view = web_contents()->GetView()->GetNativeView();
@@ skipping 456 matching lines @@
 void NativeAppWindowCocoa::FlashFrame(bool flash) {
   if (flash) {
     attention_request_id_ = [NSApp requestUserAttention:NSInformationalRequest];
   } else {
     [NSApp cancelUserAttentionRequest:attention_request_id_];
     attention_request_id_ = 0;
   }
 }
 
 bool NativeAppWindowCocoa::IsAlwaysOnTop() const {
-  return false;
+  return [window() level] == kAlwaysOnTopWindowLevel;
 }
 
 void NativeAppWindowCocoa::RenderViewHostChanged(
     content::RenderViewHost* old_host,
     content::RenderViewHost* new_host) {
   web_contents()->GetView()->Focus();
 }
 
 gfx::Insets NativeAppWindowCocoa::GetFrameInsets() const {
   if (!has_frame_)
@@ skipping 155 matching lines @@
   shell_window_->OnNativeWindowChanged();
 }
 
 void NativeAppWindowCocoa::ShowWithApp() {
   is_hidden_with_app_ = false;
   if (!is_hidden_)
     ShowInactive();
   shell_window_->OnNativeWindowChanged();
 }
 
+void NativeAppWindowCocoa::SetAlwaysOnTop(bool always_on_top) {
+  [window() setLevel:(always_on_top ? kAlwaysOnTopWindowLevel :
+                                      NSNormalWindowLevel)];
+  shell_window_->OnNativeWindowChanged();
+}
+
 void NativeAppWindowCocoa::HideWithoutMarkingHidden() {
   [window() orderOut:window_controller_];
 }
 
 NativeAppWindowCocoa::~NativeAppWindowCocoa() {
 }
 
 ShellNSWindow* NativeAppWindowCocoa::window() const {
   NSWindow* window = [window_controller_ window];
   CHECK(!window || [window isKindOfClass:[ShellNSWindow class]]);
   return static_cast<ShellNSWindow*>(window);
 }
 
 void NativeAppWindowCocoa::UpdateRestoredBounds() {
   if (IsRestored(*this))
     restored_bounds_ = [window() frame];
 }