Use Chrome file dialogs on all platforms and runtimes (fixes issue #3314)

All file dialogs irrespective of source, platform and runtime will now be
routed through CefFileDialogManager and trigger CefDialogHandler callbacks
(see issue #3293).

Adds Chrome runtime support for CefBrowserHost::RunFileDialog and
CefDialogHandler callbacks.

Adds Alloy runtime support for internal GTK file and print dialogs on Linux
subject to the following limitations:

1. Internal GTK implementation:
   - Cannot be used with multi-threaded-message-loop because Chromium's
     internal GTK implementation is not thread-safe (does not use GDK threads).
   - Dialogs will not be modal to application windows when used with off-screen
     rendering due to lack of access to the client's top-level GtkWindow.
2. Cefclient CefDialogHandler implementation:
   - Cannot be used with Views because it requires a top-level GtkWindow.

Due to the above limitations no dialog implementation is currently provided for
Views + multi-threaded-message-loop on Linux. In cases where both
implementations are supported the cefclient version is now behind an optional
`--use-client-dialogs` command-line flag.

Expressly forbids multiple simultaneous file dialogs with the internal platform
implementation which uses modal dialogs. CefDialogHandler will still be notified
and can optionally handle each request without a modal dialog (see issue #3154).

Removes some RunFileDialog parameters that are not supported by the Chrome file
dialog implementation (selected_accept_filter parameter, cef_file_dialog_mode_t
overwrite/read-only flags).

patch/patches/print_preview_123.patch

@@ -135,159 +135,6 @@ index f6098966f5b34..da78289b66155 100644
  #endif
  }
  
-diff --git chrome/browser/ui/webui/print_preview/pdf_printer_handler.cc chrome/browser/ui/webui/print_preview/pdf_printer_handler.cc
-index 86e16795ce43d..9053975ad42f6 100644
---- chrome/browser/ui/webui/print_preview/pdf_printer_handler.cc
-+++ chrome/browser/ui/webui/print_preview/pdf_printer_handler.cc
-@@ -21,6 +21,7 @@
- #include "base/values.h"
- #include "build/build_config.h"
- #include "build/chromeos_buildflags.h"
-+#include "cef/libcef/features/runtime.h"
- #include "chrome/browser/app_mode/app_mode_utils.h"
- #include "chrome/browser/browser_process.h"
- #include "chrome/browser/download/download_prefs.h"
-@@ -62,6 +63,10 @@
- #include "chromeos/lacros/lacros_service.h"
- #endif
- 
-+#if BUILDFLAG(ENABLE_CEF)
-+#include "cef/libcef/browser/alloy/alloy_dialog_util.h"
-+#endif
-+
- namespace printing {
- 
- namespace {
-@@ -414,16 +419,18 @@ void PdfPrinterHandler::SelectFile(const base::FilePath& default_filename,
-     service->GetRemote<crosapi::mojom::DriveIntegrationService>()
-         ->GetMountPointPath(
-             base::BindOnce(&PdfPrinterHandler::OnSaveLocationReady,
--                           weak_ptr_factory_.GetWeakPtr(),
-+                           weak_ptr_factory_.GetWeakPtr(), initiator,
-                            std::move(default_filename), prompt_user));
-     return;
-   }
- #endif
- 
--  OnSaveLocationReady(default_filename, prompt_user, GetSaveLocation());
-+  OnSaveLocationReady(initiator, default_filename, prompt_user,
-+                      GetSaveLocation());
- }
- 
- void PdfPrinterHandler::OnSaveLocationReady(
-+    content::WebContents* initiator,
-     const base::FilePath& default_filename,
-     bool prompt_user,
-     const base::FilePath& path) {
-@@ -441,10 +448,27 @@ void PdfPrinterHandler::OnSaveLocationReady(
-   // If the directory is empty there is no reason to create it or use the
-   // default location.
-   if (path.empty()) {
-+#if BUILDFLAG(ENABLE_CEF)
-+    if (cef::IsAlloyRuntimeEnabled()) {
-+      ShowCefSaveAsDialog(initiator, default_filename, path);
-+      return;
-+    }
-+#endif
-     OnDirectorySelected(default_filename, path);
-     return;
-   }
- 
-+  auto callback = base::BindOnce(&PdfPrinterHandler::OnDirectorySelected,
-+                                 weak_ptr_factory_.GetWeakPtr(),
-+                                 default_filename);
-+#if BUILDFLAG(ENABLE_CEF)
-+  if (cef::IsAlloyRuntimeEnabled()) {
-+    callback = base::BindOnce(&PdfPrinterHandler::ShowCefSaveAsDialog,
-+                              weak_ptr_factory_.GetWeakPtr(), initiator,
-+                              default_filename);
-+  }
-+#endif
-+
-   // Get default download directory. This will be used as a fallback if the
-   // save directory does not exist.
-   DownloadPrefs* download_prefs = DownloadPrefs::FromBrowserContext(profile_);
-@@ -452,8 +476,7 @@ void PdfPrinterHandler::OnSaveLocationReady(
-   base::ThreadPool::PostTaskAndReplyWithResult(
-       FROM_HERE, {base::MayBlock(), base::TaskPriority::BEST_EFFORT},
-       base::BindOnce(&SelectSaveDirectory, path, default_path),
--      base::BindOnce(&PdfPrinterHandler::OnDirectorySelected,
--                     weak_ptr_factory_.GetWeakPtr(), default_filename));
-+      std::move(callback));
- }
- 
- void PdfPrinterHandler::PostPrintToPdfTask() {
-@@ -499,6 +522,36 @@ void PdfPrinterHandler::OnDirectorySelected(const base::FilePath& filename,
-       platform_util::GetTopLevel(preview_web_contents_->GetNativeView()), NULL);
- }
- 
-+#if BUILDFLAG(ENABLE_CEF)
-+
-+void PdfPrinterHandler::ShowCefSaveAsDialog(content::WebContents* initiator,
-+                                            const base::FilePath& filename,
-+                                            const base::FilePath& directory) {
-+  base::FilePath path = directory.Append(filename);
-+
-+  blink::mojom::FileChooserParams params;
-+  params.mode = blink::mojom::FileChooserParams::Mode::kSave;
-+  params.default_file_name = path;
-+  params.accept_types.push_back(
-+      alloy::FilePathTypeToString16(path.Extension()));
-+
-+  alloy::RunFileChooser(initiator, params,
-+      base::BindOnce(&PdfPrinterHandler::SaveAsDialogDismissed,
-+                     weak_ptr_factory_.GetWeakPtr()));
-+}
-+
-+void PdfPrinterHandler::SaveAsDialogDismissed(
-+    int selected_accept_filter,
-+    const std::vector<base::FilePath>& file_paths) {
-+  if (file_paths.size() == 1) {
-+    FileSelected(file_paths[0], 0, nullptr);
-+  } else {
-+    FileSelectionCanceled(nullptr);
-+  }
-+}
-+
-+#endif  // BUILDFLAG(ENABLE_CEF)
-+
- base::FilePath PdfPrinterHandler::GetSaveLocation() const {
- #if BUILDFLAG(IS_CHROMEOS_ASH)
-   drive::DriveIntegrationService* drive_service =
-diff --git chrome/browser/ui/webui/print_preview/pdf_printer_handler.h chrome/browser/ui/webui/print_preview/pdf_printer_handler.h
-index 46c8b1d08b075..1ee95cd7c3240 100644
---- chrome/browser/ui/webui/print_preview/pdf_printer_handler.h
-+++ chrome/browser/ui/webui/print_preview/pdf_printer_handler.h
-@@ -12,6 +12,7 @@
- #include "base/memory/ref_counted.h"
- #include "base/memory/weak_ptr.h"
- #include "build/chromeos_buildflags.h"
-+#include "cef/libcef/features/features.h"
- #include "chrome/browser/ui/webui/print_preview/printer_handler.h"
- #include "ui/shell_dialogs/select_file_dialog.h"
- 
-@@ -95,10 +96,20 @@ class PdfPrinterHandler : public PrinterHandler,
-   void OnDirectorySelected(const base::FilePath& filename,
-                            const base::FilePath& directory);
- 
--  void OnSaveLocationReady(const base::FilePath& default_filename,
-+  void OnSaveLocationReady(content::WebContents* initiator,
-+                           const base::FilePath& default_filename,
-                            bool prompt_user,
-                            const base::FilePath& path);
- 
-+#if BUILDFLAG(ENABLE_CEF)
-+  void ShowCefSaveAsDialog(content::WebContents* initiator,
-+                           const base::FilePath& filename,
-+                           const base::FilePath& directory);
-+
-+  void SaveAsDialogDismissed(int selected_accept_filter,
-+                             const std::vector<base::FilePath>& file_paths);
-+#endif
-+
-   // Return save location as the Drive mount or fetch from Download Preferences.
-   base::FilePath GetSaveLocation() const;
- 
 diff --git chrome/browser/ui/webui/print_preview/print_preview_ui.cc chrome/browser/ui/webui/print_preview/print_preview_ui.cc
 index eba14d78d87ff..7901f000a44b5 100644
 --- chrome/browser/ui/webui/print_preview/print_preview_ui.cc