[Mac] Allow vibrancy & transparency on WebContentsView

content/browser/web_contents/web_contents_view_mac.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 <Carbon/Carbon.h>
 
 #import "content/browser/web_contents/web_contents_view_mac.h"
 
 #include <string>
 
@@ skipping 405 matching lines @@
   [self cancelDeferredClose];
 
   // This probably isn't strictly necessary, but can't hurt.
   [self unregisterDraggedTypes];
 
   [[NSNotificationCenter defaultCenter] removeObserver:self];
 
   [super dealloc];
 }
 
+- (BOOL)allowsVibrancy {
+  return YES;

[Alexei Svitkine (slow), 2015/01/22 16:41:21]

What's the effect of returning YES here?

Does it change behavior by default or is it dependent on something else? (e.g.
the view being opaque)

If it doesn't change anything on its own, please document that here in a
comment.

(If it does change things, then probably we should make it configurable unless
Chrome decides to actually adopt the changed behavior/appearance.)

[joleksy, 2015/01/23 07:24:01]

By itself it does not change anything, from the documentation:
"AppKit checks this property when the view is incorporated into a view hierarchy
that uses vibrancy."
This means that in order to actually change how this view looks it would have to
be put inside a vibrant hierarchy (i.e. within NSVisualEffectView).
I will add comment.

+}
+
 // Registers for the view for the appropriate drag types.
 - (void)registerDragTypes {
   NSArray* types = [NSArray arrayWithObjects:
       ui::kChromeDragDummyPboardType,
       kWebURLsWithTitlesPboardType,
       NSURLPboardType,
       NSStringPboardType,
       NSHTMLPboardType,
       NSRTFPboardType,
       NSFilenamesPboardType,
@@ skipping 36 matching lines @@
 - (BOOL)mouseDownCanMoveWindow {
   // This is needed to prevent mouseDowns from moving the window
   // around.  The default implementation returns YES only for opaque
   // views.  WebContentsViewCocoa does not draw itself in any way, but
   // its subviews do paint their entire frames.  Returning NO here
   // saves us the effort of overriding this method in every possible
   // subview.
   return mouseDownCanMoveWindow_;
 }
 
+- (void)setOpaque:(BOOL)opaque {
+  RenderWidgetHostViewMac* view = static_cast<RenderWidgetHostViewMac*>(
+      webContentsView_->web_contents()->GetRenderWidgetHostView());
+  DCHECK(view);
+  [view->cocoa_view() setOpaque:opaque];
+}
+
 - (void)pasteboard:(NSPasteboard*)sender provideDataForType:(NSString*)type {
   [dragSource_ lazyWriteToPasteboard:sender
                              forType:type];
 }
 
 - (void)startDragWithDropData:(const DropData&)dropData
             dragOperationMask:(NSDragOperation)operationMask
                         image:(NSImage*)image
                        offset:(NSPoint)offset {
   dragSource_.reset([[WebDragSource alloc]
@@ skipping 138 matching lines @@
   if (window && webContents) {
     if ([window occlusionState] & NSWindowOcclusionStateVisible) {
       webContents->WasUnOccluded();
     } else {
       webContents->WasOccluded();
     }
   }
 }
 
 @end