Mac: Make it easier for views to correctly draw with a theme.

ui/base/cocoa/nsview_additions.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.
 
 #include "base/mac/sdk_forward_declarations.h"
 #import "ui/base/cocoa/nsview_additions.h"
 #include "ui/gfx/scoped_ns_graphics_context_save_gstate_mac.h"
 
 #include "base/logging.h"
 
@@ skipping 42 matching lines @@
   [self addSubview:subview
         positioned:place
         relativeTo:otherView];
 }
 
 - (NSColor*)cr_keyboardFocusIndicatorColor {
   return [[NSColor keyboardFocusIndicatorColor]
       colorWithAlphaComponent:0.5 / [self cr_lineWidth]];
 }
 
+- (void)cr_recursivelyInvokeBlock:(void (^)(id view))block {
+  block(self);
+  for (NSView* subview in [self subviews])
+    [subview cr_recursivelyInvokeBlock:block];
+}
+
 - (void)cr_recursivelySetNeedsDisplay:(BOOL)flag {
   [self setNeedsDisplay:YES];
   for (NSView* child in [self subviews])
     [child cr_recursivelySetNeedsDisplay:flag];
 }
 
 static NSView* g_ancestorBeingDrawnFrom = nil;
 static NSView* g_childBeingDrawnTo = nil;
 
 - (void)cr_drawUsingAncestor:(NSView*)ancestorView inRect:(NSRect)rect {
@@ skipping 18 matching lines @@
 }
 
 - (NSView*)cr_viewBeingDrawnTo {
   if (!g_ancestorBeingDrawnFrom)
     return self;
   DCHECK(g_ancestorBeingDrawnFrom == self);
   return g_childBeingDrawnTo;
 }
 
 @end