Teach the network service to clear its disk cache if requested.

mojo/services/network/network_service_delegate.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 "mojo/services/network/network_service_delegate.h"
 
 #include "base/at_exit.h"
 #include "base/base_paths.h"
+#include "base/command_line.h"
+#include "base/location.h"
+#include "base/bind.h"
+#include "base/threading/thread.h"
 #include "base/files/file_path.h"
 #include "base/message_loop/message_loop.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/path_service.h"
 #include "third_party/mojo/src/mojo/public/cpp/application/application_connection.h"
 
+namespace {
+void DoNothing() {
+}
+}  // namespace
+
 NetworkServiceDelegate::NetworkServiceDelegate() {}
 
 NetworkServiceDelegate::~NetworkServiceDelegate() {}
 
 void NetworkServiceDelegate::Initialize(mojo::ApplicationImpl* app) {
   tracing_.Initialize(app);
   base::FilePath base_path;
   CHECK(PathService::Get(base::DIR_TEMP, &base_path));
   base_path = base_path.Append(FILE_PATH_LITERAL("network_service"));
+  base::CommandLine command_line(app->args());
+  if (command_line.HasSwitch("clear")) {
+    scoped_ptr<base::Thread> cache_delete_thread(
+        new base::Thread("network cache delete thread"));
+    cache_delete_thread->Start();
+    mojo::NetworkContext::ClearCache(base_path,
+                                     cache_delete_thread->task_runner());
+    // base::Thread required that Stop() is called on the same thread as
+    // Start(). PostTaskAndReply() with a dummy task ensures that we call Stop()
+    // on the right thread and only after cache deletion was completed (as the
+    // thread task runner is sequential).
+    cache_delete_thread->task_runner()->PostTaskAndReply(
+        FROM_HERE, base::Bind(&DoNothing),
+        base::Bind(&base::Thread::Stop,
+                   base::Owned(cache_delete_thread.release())));

[qsr, 2015/09/16 13:27:05]

This seems hacky. Where is the guarantee that ClearCache should only post a
single task? If you start posting task in the thread, this will break badly.

ClearCache should take a callback.

[ppi, 2015/09/16 14:20:59]

Done.

+  }
   context_.reset(new mojo::NetworkContext(base_path));
 }
 
 bool NetworkServiceDelegate::ConfigureIncomingConnection(
     mojo::ApplicationConnection* connection) {
   DCHECK(context_);
   connection->AddService(this);
   return true;
 }
 
 void NetworkServiceDelegate::Quit() {
   // Destroy the NetworkContext now as it requires MessageLoop::current() upon
   // destruction and it is the last moment we know for sure that it is
   // running.
   context_.reset();
 }
 
 void NetworkServiceDelegate::Create(
     mojo::ApplicationConnection* connection,
     mojo::InterfaceRequest<mojo::NetworkService> request) {
   new mojo::NetworkServiceImpl(request.Pass(), connection, context_.get());
 }