[MacViews] Implement colored window frames.

ui/gfx/mac/nswindow_frame_controls.mm

 // Copyright 2015 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.
 
 #import "ui/gfx/mac/nswindow_frame_controls.h"
 
 #import "base/mac/mac_util.h"
 #import "base/mac/sdk_forward_declarations.h"
+#import "skia/ext/skia_utils_mac.h"
 #include "ui/gfx/geometry/size.h"
 
+@implementation TitlebarBackgroundView
+
+- (void)drawRect:(NSRect)rect {
+  // Only the top corners are rounded. For simplicity, round all 4 corners but
+  // draw the bottom corners outside of the visible bounds.
+  CGFloat cornerRadius = 4.0;
+  NSRect roundedRect = [self bounds];
+  roundedRect.origin.y -= cornerRadius;
+  roundedRect.size.height += cornerRadius;
+  [[NSBezierPath bezierPathWithRoundedRect:roundedRect
+                                   xRadius:cornerRadius
+                                   yRadius:cornerRadius] addClip];
+  if ([[self window] isMainWindow] || [[self window] isKeyWindow])
+    [color_ set];
+  else
+    [inactiveColor_ set];
+  NSRectFill(rect);
+}
+
+- (void)setColor:(NSColor*)color inactiveColor:(NSColor*)inactiveColor {
+  color_.reset([color retain]);
+  inactiveColor_.reset([inactiveColor retain]);
+}
+
+@end
+
 namespace {
 
 // The value used to represent an unbounded width or height.
 const int kUnboundedSize = 0;
 
 void SetResizableStyleMask(NSWindow* window, bool resizable) {
   NSUInteger style_mask = [window styleMask];
   if (resizable)
     style_mask |= NSResizableWindowMask;
   else
@@ skipping 32 matching lines @@
 
   // 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 windows that have unbounded size.
   if (base::mac::IsOSLionOrLater())
     SetNSWindowCanFullscreen(window, can_fullscreen);
 
   [[window standardWindowButton:NSWindowZoomButton] setEnabled:can_fullscreen];
 }
 
+void AddColoredTitlebarToNSWindow(NSWindow* window,

[tapted, 2015/05/06 02:58:29]

Can this go in chrome/browser/ui/apps ? I don't think anything but app windows
will ever want it.

[jackhou1, 2015/05/12 05:39:05]

Moved to titlebar_background_view.h|mm

+                                  SkColor active_color,
+                                  SkColor inactive_color) {
+  // AppKit only officially supports adding subviews to the window's
+  // contentView and not its superview (an NSNextStepFrame). The 10.10 SDK
+  // allows adding an NSTitlebarAccessoryViewController to a window, but the
+  // view can only be placed above the window control buttons, so we'd have to
+  // replicate those.
+  NSView* window_view = [[window contentView] superview];
+  CGFloat height =
+      NSHeight([window_view bounds]) - NSHeight([[window contentView] bounds]);
+  base::scoped_nsobject<TitlebarBackgroundView> titlebar_background_view(
+      [[TitlebarBackgroundView alloc]
+          initWithFrame:NSMakeRect(0, NSMaxY([window_view bounds]) - height,
+                                   NSWidth([window_view bounds]), height)]);
+  [titlebar_background_view
+      setAutoresizingMask:NSViewWidthSizable | NSViewMinYMargin];
+  [window_view addSubview:titlebar_background_view
+               positioned:NSWindowBelow
+               relativeTo:nil];
+  [titlebar_background_view setColor:gfx::SkColorToSRGBNSColor(active_color)
+                       inactiveColor:gfx::SkColorToSRGBNSColor(inactive_color)];
+}
+
 }  // namespace gfx