Use 0 to represent process_id of browser process when creating a URLLoaderFactory.

This is per the NetworkContext::CreateURLLoaderFactory contract.

BUG=770854

Change-Id: I4ae9fb610d1860948c84fa9126e98d260afbdfbd
Reviewed-on: https://chromium-review.googlesource.com/745161Reviewed-by: Matt Menke <mmenke@chromium.org>
Commit-Queue: John Abd-El-Malek <jam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#512832}

chrome/browser/net/system_network_context_manager.cc

@@ -91,7 +91,7 @@ content::mojom::URLLoaderFactory*
 SystemNetworkContextManager::GetURLLoaderFactory() {
   if (!url_loader_factory_) {
     GetContext()->CreateURLLoaderFactory(
-        mojo::MakeRequest(&url_loader_factory_), base::GetUniqueIdForProcess());
+        mojo::MakeRequest(&url_loader_factory_), 0);
   }
   return url_loader_factory_.get();
 }

content/browser/storage_partition_impl.cc

@@ -607,8 +607,7 @@ StoragePartitionImpl::GetURLLoaderFactoryForBrowserProcess() {
   // Create the URLLoaderFactory as needed.
   if (!url_loader_factory_for_browser_process_) {
     GetNetworkContext()->CreateURLLoaderFactory(
-        mojo::MakeRequest(&url_loader_factory_for_browser_process_),
-        base::GetUniqueIdForProcess());
+        mojo::MakeRequest(&url_loader_factory_for_browser_process_), 0);
   }
   return url_loader_factory_for_browser_process_.get();
 }