[Files SWA]: Use WeakPtr to prevent a possible UAR bug.

UAR = use after release.

Bug: 1290008

Change-Id: I8ec1cab58830a6e12468523b737ee589cfe8e23a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3426095
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: Bo Majewski <majewski@chromium.org>
Cr-Commit-Position: refs/heads/main@{#965077}

chrome/browser/ui/views/select_file_dialog_extension.cc

@@ -194,13 +194,13 @@ SelectFileDialogExtension::RoutingID GetRoutingID(
 class SystemFilesAppDialogDelegate : public chromeos::SystemWebDialogDelegate,
                                      public ash::ColorModeObserver {
  public:
-  SystemFilesAppDialogDelegate(SelectFileDialogExtension* parent,
+  SystemFilesAppDialogDelegate(base::WeakPtr<SelectFileDialogExtension> parent,
                                const std::string& id,
                                GURL url,
                                std::u16string title)
       : chromeos::SystemWebDialogDelegate(url, title),
         id_(id),
-        parent_(parent) {
+        parent_(std::move(parent)) {
     ash::ColorProvider::Get()->AddObserver(this);
   }
   ~SystemFilesAppDialogDelegate() override {
@@ -240,11 +240,17 @@ class SystemFilesAppDialogDelegate : public chromeos::SystemWebDialogDelegate,
   }
 
   void OnDialogShown(content::WebUI* webui) override {
-    parent_->OnSystemDialogShown(webui->GetWebContents(), id_);
+    if (parent_) {
+      parent_->OnSystemDialogShown(webui->GetWebContents(), id_);
+    }
     chromeos::SystemWebDialogDelegate::OnDialogShown(webui);
   }
 
-  void OnDialogWillClose() override { parent_->OnSystemDialogWillClose(); }
+  void OnDialogWillClose() override {
+    if (parent_) {
+      parent_->OnSystemDialogWillClose();
+    }
+  }
 
   void OnColorModeChanged(bool dark_mode_enabled) override {
     auto* color_provider = ash::ColorProvider::Get();
@@ -263,7 +269,7 @@ class SystemFilesAppDialogDelegate : public chromeos::SystemWebDialogDelegate,
   const std::string id_;
 
   // The parent of this delegate.
-  SelectFileDialogExtension* parent_;
+  base::WeakPtr<SelectFileDialogExtension> parent_;
 };
 
 /////////////////////////////////////////////////////////////////////////////
@@ -536,11 +542,8 @@ void SelectFileDialogExtension::SelectFileWithFileManagerParams(
       base_window ? base_window->GetNativeWindow() : owner.window;
 
   if (ash::features::IsFileManagerSwaEnabled()) {
-    // SystemFilesAppDialogDelegate is a self-deleting class that calls the
-    // delete operator once the dialog for which it was created has been closed.
-    // Hence this memory-leak looking code pattern.
     auto* dialog_delegate = new SystemFilesAppDialogDelegate(
-        this, routing_id, file_manager_url, dialog_title);
+        weak_factory_.GetWeakPtr(), routing_id, file_manager_url, dialog_title);
     dialog_delegate->SetModal(owner.window != nullptr);
     dialog_delegate->set_can_resize(can_resize_);
     dialog_delegate->ShowSystemDialogForBrowserContext(profile_, parent_window);

chrome/browser/ui/views/select_file_dialog_extension.h

@@ -11,6 +11,7 @@
 
 #include "ash/public/cpp/style/color_mode_observer.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "chrome/browser/ui/views/extensions/extension_dialog_observer.h"
 #include "third_party/abseil-cpp/absl/types/optional.h"
 #include "ui/gfx/native_widget_types.h"  // gfx::NativeWindow
@@ -185,6 +186,7 @@ class SelectFileDialogExtension : public ui::SelectFileDialog,
   int selection_index_ = 0;
   bool can_resize_ = true;
   void* params_ = nullptr;
+  base::WeakPtrFactory<SelectFileDialogExtension> weak_factory_{this};
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_SELECT_FILE_DIALOG_EXTENSION_H_