Use OnceCallback in PrintViewManager.

It currently uses RepeatingCallback, and resets the callback after
running it.

Also initialize members in the header and fix some nits.

Change-Id: I92248c94993fa09ab4061a7ef17f4a2a82be4d8d
Reviewed-on: https://chromium-review.googlesource.com/c/1308911Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604339}

chrome/browser/printing/print_view_manager.cc

@@ -66,11 +66,7 @@ struct PrintViewManager::FrameDispatchHelper {
 };
 
 PrintViewManager::PrintViewManager(content::WebContents* web_contents)
-    : PrintViewManagerBase(web_contents),
-      print_preview_state_(NOT_PREVIEWING),
-      print_preview_rfh_(nullptr),
-      scripted_print_preview_rph_(nullptr),
-      is_switching_to_system_dialog_(false) {
+    : PrintViewManagerBase(web_contents) {
   if (PrintPreviewDialogController::IsPrintPreviewURL(web_contents->GetURL())) {
     EnableInternalPDFPluginForContents(
         web_contents->GetMainFrame()->GetProcess()->GetID(),
@@ -83,10 +79,10 @@ PrintViewManager::~PrintViewManager() {
 }
 
 bool PrintViewManager::PrintForSystemDialogNow(
-    const base::Closure& dialog_shown_callback) {
-  DCHECK(!dialog_shown_callback.is_null());
-  DCHECK(on_print_dialog_shown_callback_.is_null());
-  on_print_dialog_shown_callback_ = dialog_shown_callback;
+    base::OnceClosure dialog_shown_callback) {
+  DCHECK(dialog_shown_callback);
+  DCHECK(!on_print_dialog_shown_callback_);
+  on_print_dialog_shown_callback_ = std::move(dialog_shown_callback);
   is_switching_to_system_dialog_ = true;
 
   SetPrintingRFH(print_preview_rfh_);
@@ -193,11 +189,8 @@ void PrintViewManager::OnDidShowPrintDialog(content::RenderFrameHost* rfh) {
   if (rfh != print_preview_rfh_)
     return;
 
-  if (on_print_dialog_shown_callback_.is_null())
-    return;
-
-  on_print_dialog_shown_callback_.Run();
-  on_print_dialog_shown_callback_.Reset();
+  if (on_print_dialog_shown_callback_)
+    std::move(on_print_dialog_shown_callback_).Run();
 }
 
 void PrintViewManager::OnSetupScriptedPrintPreview(

chrome/browser/printing/print_view_manager.h

@@ -26,7 +26,7 @@ class PrintViewManager : public PrintViewManagerBase,
   // Same as PrintNow(), but for the case where a user prints with the system
   // dialog from print preview.
   // |dialog_shown_callback| is called when the print dialog is shown.
-  bool PrintForSystemDialogNow(const base::Closure& dialog_shown_callback);
+  bool PrintForSystemDialogNow(base::OnceClosure dialog_shown_callback);
 
   // Same as PrintNow(), but for the case where a user press "ctrl+shift+p" to
   // show the native system dialog. This can happen from both initiator and
@@ -67,8 +67,9 @@ class PrintViewManager : public PrintViewManagerBase,
     SCRIPTED_PREVIEW,
   };
 
-  // IPC Message handlers.
   struct FrameDispatchHelper;
+
+  // IPC Message handlers.
   void OnDidShowPrintDialog(content::RenderFrameHost* rfh);
   void OnSetupScriptedPrintPreview(content::RenderFrameHost* rfh,
                                    IPC::Message* reply_msg);
@@ -76,21 +77,21 @@ class PrintViewManager : public PrintViewManagerBase,
                                   bool source_is_modifiable);
   void OnScriptedPrintPreviewReply(IPC::Message* reply_msg);
 
-  base::Closure on_print_dialog_shown_callback_;
+  base::OnceClosure on_print_dialog_shown_callback_;
 
   // Current state of print preview for this view.
-  PrintPreviewState print_preview_state_;
+  PrintPreviewState print_preview_state_ = NOT_PREVIEWING;
 
   // The current RFH that is print previewing. It should be a nullptr when
   // |print_preview_state_| is NOT_PREVIEWING.
-  content::RenderFrameHost* print_preview_rfh_;
+  content::RenderFrameHost* print_preview_rfh_ = nullptr;
 
   // Keeps track of the pending callback during scripted print preview.
-  content::RenderProcessHost* scripted_print_preview_rph_;
+  content::RenderProcessHost* scripted_print_preview_rph_ = nullptr;
 
   // Indicates whether we're switching from print preview to system dialog. This
   // flag is true between PrintForSystemDialogNow() and PrintPreviewDone().
-  bool is_switching_to_system_dialog_;
+  bool is_switching_to_system_dialog_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(PrintViewManager);
 };

chrome/browser/ui/webui/print_preview/print_preview_handler.cc

@@ -977,7 +977,7 @@ void PrintPreviewHandler::HandleGetAccessToken(const base::ListValue* args) {
   token_service_->RequestToken(type, callback_id);
 }
 
-// TODO (rbpotter): Remove this when the old Print Preview page is deleted.
+// TODO(rbpotter): Remove this when the old Print Preview page is deleted.
 void PrintPreviewHandler::HandleManagePrinters(const base::ListValue* args) {
   GURL local_printers_manage_url(
       chrome::GetSettingsUrl(chrome::kPrintingSettingsSubPage));
@@ -998,9 +998,8 @@ void PrintPreviewHandler::HandleShowSystemDialog(
     return;
 
   auto* print_view_manager = PrintViewManager::FromWebContents(initiator);
-  print_view_manager->PrintForSystemDialogNow(
-      base::Bind(&PrintPreviewHandler::ClosePreviewDialog,
-                 weak_factory_.GetWeakPtr()));
+  print_view_manager->PrintForSystemDialogNow(base::BindOnce(
+      &PrintPreviewHandler::ClosePreviewDialog, weak_factory_.GetWeakPtr()));
 
   // Cancel the pending preview request if exists.
   print_preview_ui()->OnCancelPendingPreviewRequest();