DevTools: speculative fix for crash in NetworkHandler::Disable

This keeps BrowserContext* and StoragePartition* instead of
RenderProcessHost* in an attemp to resolve UAF of RenderProcessHost
upon closure of DevTools front-end.

Bug: 801117, 783067, 780694
Change-Id: I6c2cca60cc0c29f0949d189cf918769059f80c1b
Reviewed-on: https://chromium-review.googlesource.com/876657
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531157}
 NetworkHandler::NetworkHandler(const std::string& host_id)
     : DevToolsDomainHandler(Network::Metainfo::domainName),
      browser_context_(nullptr),
      storage_partition_(nullptr),
       host_(nullptr),
       enabled_(false),
       host_id_(host_id),
      bypass_service_worker_(false),
      cache_disabled_(false),
      weak_factory_(this) {
  static bool have_configured_service_worker_context = false;
  if (have_configured_service_worker_context)
    return;
  have_configured_service_worker_context = true;
  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
                          base::BindOnce(&ConfigureServiceWorkerContextOnIO));
}

 NetworkHandler::NetworkHandler(const std::string& host_id)
     : DevToolsDomainHandler(Network::Metainfo::domainName),
      process_(nullptr),
       host_(nullptr),
       enabled_(false),
       host_id_(host_id),
      bypass_service_worker_(false),
      cache_disabled_(false),
      weak_factory_(this) {
  static bool have_configured_service_worker_context = false;
  if (have_configured_service_worker_context)
    return;
  have_configured_service_worker_context = true;
  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
                          base::BindOnce(&ConfigureServiceWorkerContextOnIO));
}
