[iOS] Initialize SafeBrowsingServiceImpl's SharedURLLoaderFactory eariler

This CL initializes SafeBrowsingServiceImpl's
SharedURLLoaderFactory in Initialize(), rather than two
thread hops after Initialize(). This ensures that
GetURLLoaderFactory() has a non-null return value when called
shortly after Initialize().

This fixes crashes that occur when CreateUrlChecker() is called
soon after Initialize(), resulting in the creation of a
RealTimeUrlLookupService that has a null URLLoaderFactory and
crashes when it tries to use it.

Bug: 1114706
Change-Id: I9142c82979954a272f351c14db20246730f720db
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2346862
Commit-Queue: Ali Juma <ajuma@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797066}

ios/chrome/browser/safe_browsing/safe_browsing_service_impl.mm

@@ -67,6 +67,17 @@ void SafeBrowsingServiceImpl::Initialize(PrefService* prefs,
                      network_context_client_.BindNewPipeAndPassReceiver(),
                      safe_browsing_data_path));
 
+  auto url_loader_factory_params =
+      network::mojom::URLLoaderFactoryParams::New();
+  url_loader_factory_params->process_id = network::mojom::kBrowserProcessId;
+  url_loader_factory_params->is_corb_enabled = false;
+  network_context_client_->CreateURLLoaderFactory(
+      url_loader_factory_.BindNewPipeAndPassReceiver(),
+      std::move(url_loader_factory_params));
+  shared_url_loader_factory_ =
+      base::MakeRefCounted<network::WeakWrapperSharedURLLoaderFactory>(
+          url_loader_factory_.get());
+
   // Watch for changes to the Safe Browsing opt-out preference.
   pref_change_registrar_ = std::make_unique<PrefChangeRegistrar>();
   pref_change_registrar_->Init(prefs);
@@ -133,17 +144,7 @@ void SafeBrowsingServiceImpl::ClearCookies(
 void SafeBrowsingServiceImpl::SetUpURLLoaderFactory(
     mojo::PendingReceiver<network::mojom::URLLoaderFactory> receiver) {
   DCHECK_CURRENTLY_ON(web::WebThread::UI);
-  auto url_loader_factory_params =
-      network::mojom::URLLoaderFactoryParams::New();
-  url_loader_factory_params->process_id = network::mojom::kBrowserProcessId;
-  url_loader_factory_params->is_corb_enabled = false;
-  network_context_client_->CreateURLLoaderFactory(
-      url_loader_factory_.BindNewPipeAndPassReceiver(),
-      std::move(url_loader_factory_params));
   url_loader_factory_->Clone(std::move(receiver));
-  shared_url_loader_factory_ =
-      base::MakeRefCounted<network::WeakWrapperSharedURLLoaderFactory>(
-          url_loader_factory_.get());
 }
 
 void SafeBrowsingServiceImpl::UpdateSafeBrowsingEnabledState() {

ios/chrome/browser/safe_browsing/safe_browsing_service_unittest.mm

@@ -416,3 +416,27 @@ TEST_F(SafeBrowsingServiceTest, ClearCookies) {
       }));
   run_loop5.Run();
 }
+
+using SafeBrowsingServiceInitializationTest = PlatformTest;
+
+// Verifies that GetURLLoaderFactory() has a non-null return value when called
+// immediately after initialization.
+TEST_F(SafeBrowsingServiceInitializationTest, GetURLLoaderFactory) {
+  web::WebTaskEnvironment task_environment;
+
+  TestChromeBrowserState::Builder builder;
+  std::unique_ptr<TestChromeBrowserState> browser_state = builder.Build();
+
+  base::ScopedTempDir temp_dir;
+  ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
+
+  scoped_refptr<SafeBrowsingService> safe_browsing_service =
+      base::MakeRefCounted<SafeBrowsingServiceImpl>();
+  safe_browsing_service->Initialize(browser_state->GetPrefs(),
+                                    temp_dir.GetPath());
+
+  EXPECT_TRUE(safe_browsing_service->GetURLLoaderFactory());
+
+  safe_browsing_service->ShutDown();
+  base::RunLoop().RunUntilIdle();
+}