refactor: cleanup how WebContents is destroyed (#27920)

shell/browser/ui/cocoa/electron_inspectable_web_contents_view.h

@@ -34,13 +34,13 @@ using electron::InspectableWebContentsViewMac;
   BOOL devtools_visible_;
   BOOL devtools_docked_;
   BOOL devtools_is_first_responder_;
+  BOOL attached_to_window_;
 
   DevToolsContentsResizingStrategy strategy_;
 }
 
 - (instancetype)initWithInspectableWebContentsViewMac:
     (InspectableWebContentsViewMac*)view;
-- (void)removeObservers;
 - (void)notifyDevToolsFocused;
 - (void)setDevToolsVisible:(BOOL)visible activate:(BOOL)activate;
 - (BOOL)isDevToolsVisible;

shell/browser/ui/cocoa/electron_inspectable_web_contents_view.mm

@@ -35,18 +35,7 @@
   devtools_visible_ = NO;
   devtools_docked_ = NO;
   devtools_is_first_responder_ = NO;
-
-  [[NSNotificationCenter defaultCenter]
-      addObserver:self
-         selector:@selector(viewDidBecomeFirstResponder:)
-             name:kViewDidBecomeFirstResponder
-           object:nil];
-
-  [[NSNotificationCenter defaultCenter]
-      addObserver:self
-         selector:@selector(parentWindowBecameMain:)
-             name:NSWindowDidBecomeMainNotification
-           object:nil];
+  attached_to_window_ = NO;
 
   if (inspectableWebContentsView_->inspectable_web_contents()->IsGuest()) {
     fake_view_.reset([[NSView alloc] init]);
@@ -69,14 +58,34 @@
   return self;
 }
 
-- (void)removeObservers {
+- (void)dealloc {
   [[NSNotificationCenter defaultCenter] removeObserver:self];
+  [super dealloc];
 }
 
 - (void)resizeSubviewsWithOldSize:(NSSize)oldBoundsSize {
   [self adjustSubviews];
 }
 
+- (void)viewDidMoveToWindow {
+  if (attached_to_window_ && !self.window) {
+    attached_to_window_ = NO;
+    [[NSNotificationCenter defaultCenter] removeObserver:self];
+  } else if (!attached_to_window_ && self.window) {
+    attached_to_window_ = YES;
+    [[NSNotificationCenter defaultCenter]
+        addObserver:self
+           selector:@selector(viewDidBecomeFirstResponder:)
+               name:kViewDidBecomeFirstResponder
+             object:nil];
+    [[NSNotificationCenter defaultCenter]
+        addObserver:self
+           selector:@selector(parentWindowBecameMain:)
+               name:NSWindowDidBecomeMainNotification
+             object:nil];
+  }
+}
+
 - (IBAction)showDevTools:(id)sender {
   inspectableWebContentsView_->inspectable_web_contents()->ShowDevTools(true);
 }
@@ -253,8 +262,7 @@
 - (void)viewDidBecomeFirstResponder:(NSNotification*)notification {
   auto* inspectable_web_contents =
       inspectableWebContentsView_->inspectable_web_contents();
-  if (!inspectable_web_contents || inspectable_web_contents->IsGuest())
-    return;
+  DCHECK(inspectable_web_contents);
   auto* webContents = inspectable_web_contents->GetWebContents();
   auto* webContentsView = webContents->GetNativeView().GetNativeNSView();