[Cocoa] Clean-up: Update comments regarding drawRect override in TabContentsContainerView.

chrome/browser/ui/cocoa/tab_contents/tab_contents_controller.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/tab_contents/tab_contents_controller.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/mac/scoped_cftyperef.h"
@@ skipping 100 matching lines @@
     return [NSColor whiteColor];
 
   // Fill with a dark tint of the new tab page's background color.  This is
   // only seen when the subview is sized specially for fullscreen tab capture.
   NSColor* bgColor = nil;
   ThemeService* const theme =
       static_cast<ThemeService*>([[self window] themeProvider]);
   if (theme)
     bgColor = theme->GetNSColor(ThemeProperties::COLOR_NTP_BACKGROUND);
   if (!bgColor)
-    bgColor = [[self window] backgroundColor];
+    bgColor = [NSColor whiteColor];

[miu, 2014/06/06 01:09:10]

The decision (in https://codereview.chromium.org/244043002) was to make the
default whiteColor, so I made this the same as in line 111 above.

   const float kDarknessFraction = 0.80f;
   return [bgColor blendedColorWithFraction:kDarknessFraction
                                    ofColor:[NSColor blackColor]];
 }
 
-// Override -drawRect to fill the view with a solid color outside of the
-// subview's frame.
-- (void)drawRect:(NSRect)dirtyRect {
-  NSView* const contentsView =
-      [[self subviews] count] > 0 ? [[self subviews] objectAtIndex:0] : nil;
-  if (!contentsView || !NSContainsRect([contentsView frame], dirtyRect)) {
-    [[self computeBackgroundColor] setFill];
-    NSRectFill(dirtyRect);
-  }
-  [super drawRect:dirtyRect];
-}
-
 // Override auto-resizing logic to query the delegate for the exact frame to
 // use for the contents view.
 - (void)resizeSubviewsWithOldSize:(NSSize)oldBoundsSize {
   NSView* const contentsView =
       [[self subviews] count] > 0 ? [[self subviews] objectAtIndex:0] : nil;
   if (!contentsView || [contentsView autoresizingMask] == NSViewNotSizable ||
       !delegate_) {
     return;
   }
 
@@ skipping 77 matching lines @@
   [contentsNativeView setFrame:[self frameForContentsView]];
   if ([subviews count] == 0) {
     [contentsContainer addSubview:contentsNativeView];
   } else if ([subviews objectAtIndex:0] != contentsNativeView) {
     [contentsContainer replaceSubview:[subviews objectAtIndex:0]
                                  with:contentsNativeView];
   }
   [contentsNativeView setAutoresizingMask:NSViewWidthSizable|
                                           NSViewHeightSizable];
 
-  // TODO(miu): The following can be removed once we use a CALayer in
-  // TabContentsContainerView.  http://crbug.com/354598
   [contentsContainer setNeedsDisplay:YES];

[miu, 2014/06/06 01:09:10]

I kept this call to setNeedsDisplay since this will cause setNeedsDisplayInRect
(line 150ish above) to re-compute the background color.  This is useful both for
making sure the right background color is set each time a tab is unhidden, as
well as when a user theme settings change may necessitate a change in color.

 
   // The rendering path with overlapping views disabled causes bugs when
   // transitioning between composited and non-composited mode.
   // http://crbug.com/279472
   if (!fullscreenView)
     contents_->SetAllowOverlappingViews(true);
 }
 
 - (void)changeWebContents:(WebContents*)newContents {
   contents_ = newContents;
@@ skipping 107 matching lines @@
     } else {
       rect.ClampToCenteredSize(gfx::Size(
           static_cast<int>(x / captureSize.height()), rect.height()));
     }
   }
 
   return NSRectFromCGRect(rect.ToCGRect());
 }
 
 @end