Make the screenshare notification window 85% opaque.

chrome/browser/ui/cocoa/screen_capture_notification_ui_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/screen_capture_notification_ui_cocoa.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/compiler_specific.h"
 #include "base/i18n/rtl.h"
@@ skipping 14 matching lines @@
 #include "ui/gfx/image/image_skia_util_mac.h"
 #include "ui/gfx/text_elider.h"
 #include "ui/native_theme/native_theme.h"
 
 const CGFloat kMinimumWidth = 460;
 const CGFloat kMaximumWidth = 1000;
 const CGFloat kHorizontalMargin = 10;
 const CGFloat kPadding = 5;
 const CGFloat kPaddingLeft = 10;
 const CGFloat kWindowCornerRadius = 2;
+const CGFloat kWindowAlphaValue = 0.85;
 
 @interface ScreenCaptureNotificationController()
 - (void)hide;
 - (void)populateWithText:(const base::string16&)text;
 @end
 
 @interface ScreenCaptureNotificationView : NSView
 @end
 
 @interface WindowGripView : NSImageView
@@ skipping 28 matching lines @@
 
 @implementation ScreenCaptureNotificationController
 - (id)initWithCallback:(const base::Closure&)stop_callback
                   text:(const base::string16&)text {
   base::scoped_nsobject<NSWindow> window(
       [[NSWindow alloc] initWithContentRect:ui::kWindowSizeDeterminedLater
                                   styleMask:NSBorderlessWindowMask
                                     backing:NSBackingStoreBuffered
                                       defer:NO]);
   [window setReleasedWhenClosed:NO];
+  [window setAlphaValue:kWindowAlphaValue];
   [window setBackgroundColor:[NSColor clearColor]];
   [window setOpaque:NO];
   [window setHasShadow:YES];
   [window setLevel:NSStatusWindowLevel];
   [window setMovableByWindowBackground:YES];
   [window setDelegate:self];
 
   self = [super initWithWindow:window];
   if (self) {
     stop_callback_ = stop_callback;
@@ skipping 148 matching lines @@
   self = [super
       initWithFrame:NSMakeRect(0, 0, gripImage.Width(), gripImage.Height())];
   [self setImage:gripImage.ToNSImage()];
   return self;
 }
 
 - (BOOL)mouseDownCanMoveWindow {
   return YES;
 }
 @end