[Mac] Make app window backgrounds white.

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/foundation_util.h"
 #include "base/mac/mac_util.h"
@@ skipping 218 matching lines @@
 // Similar to ChromeBrowserWindow, don't draw the title, but allow it to be seen
 // in menus, Expose, etc.
 - (BOOL)_isTitleHidden {
   // Only intervene with 10.6-10.9.
   if ([self respondsToSelector:@selector(setTitleVisibility:)])
     return [super _isTitleHidden];
   else
     return YES;
 }
 
+- (void)drawCustomFrameRect:(NSRect)frameRect forView:(NSView*)view {
+  // Make the background color of the content area white. We can't just call
+  // -setBackgroundColor as that causes the title bar to be drawn in a solid
+  // color.
+  NSRect rect = [self contentRectForFrameRect:frameRect];
+  [[NSColor whiteColor] set];
+  NSRectFill(rect);
+
+  // Draw the native title bar. We remove the content area since the native
+  // implementation draws a gray background.
+  rect.origin.y = NSMaxY(rect);
+  rect.size.height = CGFLOAT_MAX;
+  rect = NSIntersectionRect(rect, frameRect);
+
+  [NSBezierPath clipRect:rect];
+  [super drawCustomFrameRect:frameRect
+                     forView:view];
+}
+
 @end
 
 @interface ShellCustomFrameNSWindow : ShellNSWindow {
  @private
   base::scoped_nsobject<NSColor> color_;
   base::scoped_nsobject<NSColor> inactiveColor_;
 }
 
 - (void)setColor:(NSColor*)color
     inactiveColor:(NSColor*)inactiveColor;
@@ skipping 733 matching lines @@
 }
 
 void NativeAppWindowCocoa::UpdateRestoredBounds() {
   if (IsRestored(*this))
     restored_bounds_ = [window() frame];
 }
 
 void NativeAppWindowCocoa::HideWithoutMarkingHidden() {
   [window() orderOut:window_controller_];
 }