Fix hangs in Mandoline page cycler on Linux with --enable-multiprocess.

components/pdf_viewer/pdf_viewer.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/containers/hash_tables.h"
 #include "base/memory/scoped_ptr.h"
 #include "components/mus/public/cpp/scoped_window_ptr.h"
 #include "components/mus/public/cpp/types.h"
@@ skipping 491 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(PDFView);
 };
 
 // Responsible for managing all the views for displaying a PDF document.
 class PDFViewerApplicationDelegate
     : public mojo::ApplicationDelegate,
       public mojo::InterfaceFactory<mus::mojom::WindowTreeClient> {
  public:
   PDFViewerApplicationDelegate(
       mojo::InterfaceRequest<mojo::Application> request,
-      mojo::URLResponsePtr response)
+      mojo::URLResponsePtr response,
+      const mojo::Callback<void()>& destruct_callback)
       : app_(this,
              request.Pass(),
              base::Bind(&PDFViewerApplicationDelegate::OnTerminate,
                         base::Unretained(this))),
         doc_(nullptr),
-        is_destroying_(false) {
+        is_destroying_(false),
+        destruct_callback_(destruct_callback) {
     FetchPDF(response.Pass());
   }
 
   ~PDFViewerApplicationDelegate() override {
     is_destroying_ = true;
     if (doc_)
       FPDF_CloseDocument(doc_);
     while (!pdf_views_.empty())
       pdf_views_.front()->Close();
+    destruct_callback_.Run();
   }
 
  private:
   void FetchPDF(mojo::URLResponsePtr response) {
     data_.clear();
     mojo::common::BlockingCopyToString(response->body.Pass(), &data_);
     if (data_.length() >= static_cast<size_t>(std::numeric_limits<int>::max()))
       return;
     doc_ = FPDF_LoadMemDocument(data_.data(), static_cast<int>(data_.length()),
                                 nullptr);
@@ skipping 29 matching lines @@
     mus::WindowTreeConnection::Create(
         pdf_view, request.Pass(),
         mus::WindowTreeConnection::CreateType::DONT_WAIT_FOR_EMBED);
   }
 
   mojo::ApplicationImpl app_;
   std::string data_;
   std::vector<PDFView*> pdf_views_;
   FPDF_DOCUMENT doc_;
   bool is_destroying_;
+  mojo::Callback<void()> destruct_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(PDFViewerApplicationDelegate);
 };
 
 class ContentHandlerImpl : public mojo::ContentHandler {
  public:
   ContentHandlerImpl(mojo::InterfaceRequest<ContentHandler> request)
       : binding_(this, request.Pass()) {}
   ~ContentHandlerImpl() override {}
 
  private:
   // ContentHandler:
-  void StartApplication(mojo::InterfaceRequest<mojo::Application> request,
-                        mojo::URLResponsePtr response) override {
-    new PDFViewerApplicationDelegate(request.Pass(), response.Pass());
+  void StartApplication(
+      mojo::InterfaceRequest<mojo::Application> request,
+      mojo::URLResponsePtr response,
+      const mojo::Callback<void()>& destruct_callback) override {
+    new PDFViewerApplicationDelegate(
+        request.Pass(), response.Pass(), destruct_callback);
   }
 
   mojo::StrongBinding<mojo::ContentHandler> binding_;
 
   DISALLOW_COPY_AND_ASSIGN(ContentHandlerImpl);
 };
 
 class PDFViewer : public mojo::ApplicationDelegate,
                   public mojo::InterfaceFactory<mojo::ContentHandler> {
  public:
@@ skipping 26 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(PDFViewer);
 };
 }  // namespace
 }  // namespace pdf_viewer
 
 MojoResult MojoMain(MojoHandle application_request) {
   mojo::ApplicationRunner runner(new pdf_viewer::PDFViewer());
   return runner.Run(application_request);
 }