Avoid using mojo::WrapCallbackWithDefaultInvokeIfNotRun.

Since WrapCallbackWithDefaultInvokeIfNotRun() should be used sparingly,
replace it with code to handle a disconnect in arc::PrintSessionImpl.
Now, arc::PrintSessionImpl manages pending callbacks, and handles PDF
Flattener disconnects.

Bug: 997243
Change-Id: I8a0be44998ce1eec93f166f1776e0595d15e714b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1995941
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Jesse Schettler <jschettler@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#731763}

chrome/browser/chromeos/arc/print_spooler/print_session_impl.cc

@@ -28,7 +28,6 @@
 #include "content/public/browser/web_contents.h"
 #include "mojo/public/c/system/types.h"
 #include "mojo/public/cpp/base/shared_memory_utils.h"
-#include "mojo/public/cpp/bindings/callback_helpers.h"
 #include "net/base/filename_util.h"
 #include "printing/page_range.h"
 #include "printing/print_job_constants.h"
@@ -265,13 +264,16 @@ void PrintSessionImpl::CreatePreviewDocument(
     return;
   }
 
+  int request_id = job_settings.FindIntKey(printing::kPreviewRequestID).value();
   instance_->CreatePreviewDocument(
       std::move(request),
       base::BindOnce(&PrintSessionImpl::OnPreviewDocumentCreated,
-                     weak_ptr_factory_.GetWeakPtr(), std::move(callback)));
+                     weak_ptr_factory_.GetWeakPtr(), request_id,
+                     std::move(callback)));
 }
 
 void PrintSessionImpl::OnPreviewDocumentCreated(
+    int request_id,
     CreatePreviewDocumentCallback callback,
     mojo::ScopedHandle preview_document,
     int64_t data_size) {
@@ -286,10 +288,12 @@ void PrintSessionImpl::OnPreviewDocumentCreated(
       base::BindOnce(&ReadPreviewDocument, std::move(preview_document),
                      static_cast<size_t>(data_size)),
       base::BindOnce(&PrintSessionImpl::OnPreviewDocumentRead,
-                     weak_ptr_factory_.GetWeakPtr(), std::move(callback)));
+                     weak_ptr_factory_.GetWeakPtr(), request_id,
+                     std::move(callback)));
 }
 
 void PrintSessionImpl::OnPreviewDocumentRead(
+    int request_id,
     CreatePreviewDocumentCallback callback,
     base::ReadOnlySharedMemoryRegion preview_document_region) {
   if (!preview_document_region.IsValid()) {
@@ -300,11 +304,34 @@ void PrintSessionImpl::OnPreviewDocumentRead(
   if (!pdf_flattener_.is_bound()) {
     GetPrintingService()->BindPdfFlattener(
         pdf_flattener_.BindNewPipeAndPassReceiver());
+    pdf_flattener_.set_disconnect_handler(
+        base::BindOnce(&PrintSessionImpl::OnPdfFlattenerDisconnected,
+                       weak_ptr_factory_.GetWeakPtr()));
   }
+
+  bool inserted =
+      callbacks_.emplace(std::make_pair(request_id, std::move(callback)))
+          .second;
+  DCHECK(inserted);
+
   pdf_flattener_->FlattenPdf(
       std::move(preview_document_region),
-      mojo::WrapCallbackWithDefaultInvokeIfNotRun(
-          std::move(callback), base::ReadOnlySharedMemoryRegion()));
+      base::BindOnce(&PrintSessionImpl::OnPdfFlattened,
+                     weak_ptr_factory_.GetWeakPtr(), request_id));
+}
+
+void PrintSessionImpl::OnPdfFlattened(
+    int request_id,
+    base::ReadOnlySharedMemoryRegion flattened_document_region) {
+  auto it = callbacks_.find(request_id);
+  std::move(it->second).Run(std::move(flattened_document_region));
+  callbacks_.erase(it);
+}
+
+void PrintSessionImpl::OnPdfFlattenerDisconnected() {
+  for (auto& it : callbacks_)
+    std::move(it.second).Run(base::ReadOnlySharedMemoryRegion());
+  callbacks_.clear();
 }
 
 void PrintSessionImpl::Close() {

chrome/browser/chromeos/arc/print_spooler/print_session_impl.h

@@ -7,7 +7,7 @@
 
 #include <memory>
 
-#include "base/macros.h"
+#include "base/containers/flat_map.h"
 #include "base/memory/read_only_shared_memory_region.h"
 #include "base/memory/weak_ptr.h"
 #include "base/values.h"
@@ -44,6 +44,8 @@ class PrintSessionImpl : public mojom::PrintSessionHost,
       std::unique_ptr<ash::ArcCustomTab> custom_tab,
       mojom::PrintSessionInstancePtr instance);
 
+  PrintSessionImpl(const PrintSessionImpl&) = delete;
+  PrintSessionImpl& operator=(const PrintSessionImpl&) = delete;
   ~PrintSessionImpl() override;
 
   // Called when print preview is closed.
@@ -63,16 +65,24 @@ class PrintSessionImpl : public mojom::PrintSessionHost,
   // Called once the preview document has been created by ARC. The preview
   // document must be read and flattened before being returned by the
   // PrintRenderer.
-  void OnPreviewDocumentCreated(CreatePreviewDocumentCallback callback,
+  void OnPreviewDocumentCreated(int request_id,
+                                CreatePreviewDocumentCallback callback,
                                 mojo::ScopedHandle preview_document,
                                 int64_t data_size);
 
   // Called once the preview document from ARC has been read. The preview
   // document must be flattened before being returned by the PrintRenderer.
   void OnPreviewDocumentRead(
+      int request_id,
       CreatePreviewDocumentCallback callback,
       base::ReadOnlySharedMemoryRegion preview_document_region);
 
+  void OnPdfFlattened(
+      int request_id,
+      base::ReadOnlySharedMemoryRegion flattened_document_region);
+
+  void OnPdfFlattenerDisconnected();
+
   // Used to close the ARC Custom Tab used for printing. If the remote end
   // closes the connection, the ARC Custom Tab and print preview will be closed.
   // If printing has already started, this will not cancel any active print job.
@@ -98,13 +108,14 @@ class PrintSessionImpl : public mojom::PrintSessionHost,
   // Remote interface used to flatten a PDF (preview document).
   mojo::Remote<printing::mojom::PdfFlattener> pdf_flattener_;
 
+  // In flight callbacks to |pdf_flattener_|, with their request IDs as the key.
+  base::flat_map<int, CreatePreviewDocumentCallback> callbacks_;
+
   WEB_CONTENTS_USER_DATA_KEY_DECL();
 
   // Note: This should remain the last member so it'll be destroyed and
   // invalidate its weak pointers before any other members are destroyed.
   base::WeakPtrFactory<PrintSessionImpl> weak_ptr_factory_{this};
-
-  DISALLOW_COPY_AND_ASSIGN(PrintSessionImpl);
 };
 
 }  // namespace arc