[Mac] Avoid "adding unknown subview" warning.

chrome/browser/ui/cocoa/tabs/tab_view.mm

 // Copyright (c) 2012 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 "chrome/browser/ui/cocoa/tabs/tab_view.h"
 
 #include "base/i18n/rtl.h"
 #include "base/logging.h"
 #include "base/mac/sdk_forward_declarations.h"
 #include "base/strings/sys_string_conversions.h"
@@ skipping 33 matching lines @@
 const NSTimeInterval kAlertHideDuration = 0.4;
 
 // The default time interval in seconds between glow updates (when
 // increasing/decreasing).
 const NSTimeInterval kGlowUpdateInterval = 0.025;
 
 // This is used to judge whether the mouse has moved during rapid closure; if it
 // has moved less than the threshold, we want to close the tab.
 const CGFloat kRapidCloseDist = 2.5;
 
+@interface NSView (PrivateAPI)
+// Called by AppKit to check if dragging this view should move the window.
+// NSButton overrides this method in the same way so dragging window buttons
+// has no effect. NSView implementation returns NSZeroRect so the whole view
+// area can be dragged.
+- (NSRect)_opaqueRectForWindowMoveWhenInTitlebar;
+@end
+
 // This class contains the logic for drawing Material Design tab images. The
 // |setTabEdgeStrokeColor| method is overridden by |TabHeavyImageMaker| to draw
 // high-contrast tabs.
 @interface TabImageMaker : NSObject
 + (void)drawTabLeftMaskImage;
 + (void)drawTabRightMaskImage;
 + (void)drawTabLeftEdgeImage;
 + (void)drawTabMiddleEdgeImage;
 + (void)drawTabRightEdgeImage;
 + (void)setTabEdgeStrokeColor;
@@ skipping 148 matching lines @@
   // Cancel any delayed requests that may still be pending (drags or hover).
   [NSObject cancelPreviousPerformRequestsWithTarget:self];
   if (&NSWorkspaceAccessibilityDisplayOptionsDidChangeNotification) {
     NSNotificationCenter* center =
         [[NSWorkspace sharedWorkspace] notificationCenter];
     [center removeObserver:self];
   }
   [super dealloc];
 }
 
+// Called by AppKit to check if dragging this view should move the window.
+// NSButton overrides this method in the same way so dragging window buttons
+// has no effect.
+- (NSRect)_opaqueRectForWindowMoveWhenInTitlebar {
+  return [self bounds];
+}
+
 // Called to obtain the context menu for when the user hits the right mouse
 // button (or control-clicks). (Note that -rightMouseDown: is *not* called for
 // control-click.)
 - (NSMenu*)menu {
   if ([self isClosing])
     return nil;
 
   return [controller_ menu];
 }
 
@@ skipping 770 matching lines @@
 
 // For "Increase Contrast" mode, use flat black instead of semitransparent black
 // for the tab edge stroke.
 + (void)setTabEdgeStrokeColor {
   static NSColor* heavyStrokeColor =
       [skia::SkColorToSRGBNSColor(SK_ColorBLACK) retain];
   [heavyStrokeColor set];
 }
 
 @end