refactor: use C++20's contains() method (#45742)

* chore: use std::map<>::contains() instead of count() or find()

* chore: use std::map<>::contains() instead of base::Contains()

shell/browser/ui/cocoa/electron_touch_bar.mm

@@ -334,7 +334,7 @@ static NSString* const ImageScrubberItemIdentifier = @"scrubber.image.item";
 }
 
 - (bool)hasItemWithID:(const std::string&)item_id {
-  return settings_.find(item_id) != settings_.end();
+  return settings_.contains(item_id);
 }
 
 - (NSColor*)colorFromHexColorString:(const std::string&)colorString {

shell/browser/ui/message_box_gtk.cc

@@ -4,7 +4,6 @@
 
 #include "shell/browser/ui/message_box.h"
 
-#include "base/containers/contains.h"
 #include "base/containers/flat_map.h"
 #include "base/functional/bind.h"
 #include "base/memory/raw_ptr.h"
@@ -232,7 +231,7 @@ int ShowMessageBoxSync(const MessageBoxSettings& settings) {
 
 void ShowMessageBox(const MessageBoxSettings& settings,
                     MessageBoxCallback callback) {
-  if (settings.id && base::Contains(GetDialogsMap(), *settings.id))
+  if (settings.id && GetDialogsMap().contains(*settings.id))
     CloseMessageBox(*settings.id);
   (new GtkMessageBox(settings))->RunAsynchronous(std::move(callback));
 }

shell/browser/ui/message_box_mac.mm

@@ -8,7 +8,6 @@
 
 #import <Cocoa/Cocoa.h>
 
-#include "base/containers/contains.h"
 #include "base/containers/flat_map.h"
 #include "base/mac/mac_util.h"
 #include "base/no_destructor.h"
@@ -146,7 +145,7 @@ void ShowMessageBox(const MessageBoxSettings& settings,
         ret, alert.suppressionButton.state == NSControlStateValueOn);
   } else {
     if (settings.id) {
-      if (base::Contains(GetDialogsMap(), *settings.id))
+      if (GetDialogsMap().contains(*settings.id))
         CloseMessageBox(*settings.id);
       GetDialogsMap()[*settings.id] = alert;
     }

shell/browser/ui/message_box_win.cc

@@ -10,7 +10,6 @@
 
 #include <vector>
 
-#include "base/containers/contains.h"
 #include "base/containers/flat_map.h"
 #include "base/no_destructor.h"
 #include "base/strings/string_util.h"
@@ -242,7 +241,7 @@ DialogResult ShowTaskDialogWstr(gfx::AcceleratedWidget parent,
   TaskDialogIndirect(&config, &id, nullptr, &verification_flag_checked);
 
   int button_id;
-  if (base::Contains(id_map, id))  // common button.
+  if (id_map.contains(id))  // common button.
     button_id = id_map[id];
   else if (id >= kIDStart)  // custom button.
     button_id = id - kIDStart;
@@ -289,7 +288,7 @@ void ShowMessageBox(const MessageBoxSettings& settings,
   // kHwndReserve in the dialogs map for now.
   HWND* hwnd = nullptr;
   if (settings.id) {
-    if (base::Contains(GetDialogsMap(), *settings.id))
+    if (GetDialogsMap().contains(*settings.id))
       CloseMessageBox(*settings.id);
     auto it = GetDialogsMap().emplace(*settings.id,
                                       std::make_unique<HWND>(kHwndReserve));