chore: stop using a `RenderWidgetHost` observer in `FileSelectHelper` (#38168)

chore: stop using a RenderWidgetHost observer in FileSelectHelper

shell/browser/file_select_helper.cc

@@ -29,8 +29,6 @@
 #include "content/public/browser/file_select_listener.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_process_host.h"
-#include "content/public/browser/render_view_host.h"
-#include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
 #include "net/base/filename_util.h"
 #include "net/base/mime_util.h"
@@ -46,8 +44,6 @@ using blink::mojom::FileChooserFileInfoPtr;
 using blink::mojom::FileChooserParams;
 using blink::mojom::FileChooserParamsPtr;
 using content::BrowserThread;
-using content::RenderViewHost;
-using content::RenderWidgetHost;
 using content::WebContents;
 
 namespace {
@@ -377,9 +373,7 @@ void FileSelectHelper::RunFileChooser(
   render_frame_host_ = render_frame_host;
   web_contents_ = WebContents::FromRenderFrameHost(render_frame_host);
   listener_ = std::move(listener);
-  observation_.Reset();
   content::WebContentsObserver::Observe(web_contents_);
-  observation_.Observe(render_frame_host_->GetRenderViewHost()->GetWidget());
 
   base::ThreadPool::PostTask(
       FROM_HERE, {base::MayBlock()},
@@ -518,13 +512,6 @@ void FileSelectHelper::EnumerateDirectoryEnd() {
   Release();
 }
 
-void FileSelectHelper::RenderWidgetHostDestroyed(
-    content::RenderWidgetHost* widget_host) {
-  render_frame_host_ = nullptr;
-  DCHECK(observation_.IsObservingSource(widget_host));
-  observation_.Reset();
-}
-
 void FileSelectHelper::RenderFrameHostChanged(
     content::RenderFrameHost* old_host,
     content::RenderFrameHost* new_host) {

shell/browser/file_select_helper.h

@@ -42,7 +42,6 @@ class FileSelectHelper : public base::RefCountedThreadSafe<
                              content::BrowserThread::DeleteOnUIThread>,
                          public ui::SelectFileDialog::Listener,
                          public content::WebContentsObserver,
-                         public content::RenderWidgetHostObserver,
                          private net::DirectoryLister::DirectoryListerDelegate {
  public:
   // disable copy
@@ -98,10 +97,6 @@ class FileSelectHelper : public base::RefCountedThreadSafe<
       void* params) override;
   void FileSelectionCanceled(void* params) override;
 
-  // content::RenderWidgetHostObserver overrides.
-  void RenderWidgetHostDestroyed(
-      content::RenderWidgetHost* widget_host) override;
-
   // content::WebContentsObserver overrides.
   void RenderFrameHostChanged(content::RenderFrameHost* old_host,
                               content::RenderFrameHost* new_host) override;
@@ -220,10 +215,6 @@ class FileSelectHelper : public base::RefCountedThreadSafe<
   struct ActiveDirectoryEnumeration;
   std::unique_ptr<ActiveDirectoryEnumeration> directory_enumeration_;
 
-  base::ScopedObservation<content::RenderWidgetHost,
-                          content::RenderWidgetHostObserver>
-      observation_{this};
-
   // Temporary files only used on OSX. This class is responsible for deleting
   // these files when they are no longer needed.
   std::vector<base::FilePath> temporary_files_;