Ladybird/AppKit: Display an audio button on tabs that are playing audio

When audio begins playing, add a button as an accessory view with a
speaker icon to indicate which tab is playing audio. This button is
currently disabled, but in the future may be used to mute the tab.

Ladybird/AppKit/UI/LadybirdWebView.h

@@ -11,6 +11,7 @@
 #include <LibURL/Forward.h>
 #include <LibWeb/CSS/PreferredColorScheme.h>
 #include <LibWeb/HTML/ActivateTab.h>
+#include <LibWeb/HTML/AudioPlayState.h>
 #include <LibWebView/Forward.h>
 
 #import <System/Cocoa.h>
@@ -30,6 +31,7 @@
 
 - (void)onTitleChange:(ByteString const&)title;
 - (void)onFaviconChange:(Gfx::Bitmap const&)bitmap;
+- (void)onAudioPlayStateChange:(Web::HTML::AudioPlayState)play_state;
 
 - (void)onNavigateBack;
 - (void)onNavigateForward;

Ladybird/AppKit/UI/LadybirdWebView.mm

@@ -809,6 +809,10 @@ static void copy_data_to_clipboard(StringView data, NSPasteboardType pasteboard_
         if (pasteboard_type)
             copy_data_to_clipboard(data, pasteboard_type);
     };
+
+    m_web_view_bridge->on_audio_play_state_changed = [self](auto play_state) {
+        [self.observer onAudioPlayStateChange:play_state];
+    };
 }
 
 - (void)selectDropdownAdd:(NSMenu*)menu item:(Web::HTML::SelectItem const&)item

Ladybird/AppKit/UI/Tab.mm

@@ -275,6 +275,27 @@ static constexpr CGFloat const WINDOW_HEIGHT = 800;
     [self updateTabTitleAndFavicon];
 }
 
+- (void)onAudioPlayStateChange:(Web::HTML::AudioPlayState)play_state
+{
+    switch (play_state) {
+    case Web::HTML::AudioPlayState::Paused:
+        [[self tab] setAccessoryView:nil];
+        break;
+
+    case Web::HTML::AudioPlayState::Playing:
+        auto* icon = [NSImage imageNamed:NSImageNameTouchBarAudioOutputVolumeHighTemplate];
+        auto* button = [NSButton buttonWithImage:icon target:nil action:nil];
+
+        // FIXME: Add a click handler to mute the tab.
+        NSButtonCell* cell = [button cell];
+        [cell setImageDimsWhenDisabled:NO];
+        [button setEnabled:NO];
+
+        [[self tab] setAccessoryView:button];
+        break;
+    }
+}
+
 - (void)onNavigateBack
 {
     [[self tabController] navigateBack:nil];