Fix 2 unittests that don't have appropriate URLRequestContext setup

This CL:
1. Fixes |AudioOutputAuthorizationHandlerTest| by using
   |net::TestURLRequestContextGetter| (The original code has an
   use-after-release issue, see bug for logs).
2. Fixes |RenderProcessHostUnitTest| by returning a valid pointer in
   |TestBrowserContext::CreateRequestContextForStoragePartition()|.

This patch doesn't have behavior change.

Bug: 826869
Change-Id: I05982ce49a9d42029cc3278fa248587820790d74
Reviewed-on: https://chromium-review.googlesource.com/1026986
Commit-Queue: Chong Zhang <chongz@chromium.org>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556127}

content/browser/renderer_host/media/audio_output_authorization_handler_unittest.cc

@@ -48,20 +48,22 @@ url::Origin SecurityOrigin() {
 
 // TestBrowserContext has a URLRequestContextGetter which uses a NullTaskRunner.
 // This causes it to be destroyed on the wrong thread. This BrowserContext
-// instead returns nullptr since it's not required by the test.
-class TestBrowserContextWithoutURLRequestContextGetter
+// instead uses the IO thread task runner for the URLRequestContextGetter.
+class TestBrowserContextWithRealURLRequestContextGetter
     : public TestBrowserContext {
  public:
-  TestBrowserContextWithoutURLRequestContextGetter() {
+  TestBrowserContextWithRealURLRequestContextGetter() {
+    request_context_ = base::MakeRefCounted<net::TestURLRequestContextGetter>(
+        BrowserThread::GetTaskRunnerForThread(BrowserThread::IO));
     salt_ = TestBrowserContext::GetMediaDeviceIDSalt();
   }
 
-  ~TestBrowserContextWithoutURLRequestContextGetter() override {}
+  ~TestBrowserContextWithRealURLRequestContextGetter() override {}
 
   net::URLRequestContextGetter* CreateRequestContext(
       ProtocolHandlerMap* protocol_handlers,
       URLRequestInterceptorScopedVector request_interceptors) override {
-    return nullptr;
+    return request_context_.get();
   }
 
   std::string GetMediaDeviceIDSalt() override { return salt_; }
@@ -69,6 +71,7 @@ class TestBrowserContextWithoutURLRequestContextGetter
   void set_media_device_id_salt(std::string salt) { salt_ = std::move(salt); }
 
  private:
+  scoped_refptr<net::TestURLRequestContextGetter> request_context_;
   std::string salt_;
 };
 
@@ -90,7 +93,7 @@ class AudioOutputAuthorizationHandlerTest : public RenderViewHostTestHarness {
 
   BrowserContext* CreateBrowserContext() override {
     // Caller takes ownership.
-    return new TestBrowserContextWithoutURLRequestContextGetter();
+    return new TestBrowserContextWithRealURLRequestContextGetter();
   }
 
   void SetUp() override {
@@ -405,7 +408,7 @@ TEST_F(AudioOutputAuthorizationHandlerTest,
   // Reset the salt and expect authorization of the device ID hashed with
   // the old salt to fail.
   auto* context =
-      static_cast<TestBrowserContextWithoutURLRequestContextGetter*>(
+      static_cast<TestBrowserContextWithRealURLRequestContextGetter*>(
           browser_context());
   context->set_media_device_id_salt("new salt");
   EXPECT_CALL(listener, Run(media::OUTPUT_DEVICE_STATUS_ERROR_NOT_FOUND, _, _,

content/browser/storage_partition_impl_map.cc

@@ -442,11 +442,8 @@ StoragePartitionImpl* StoragePartitionImplMap::Get(
     // be initialized using |url_request_context_|, which is initialized by
     // SetURLRequestContext().
     DCHECK(partition->url_loader_factory_getter());
-    // TODO(crbug.com/826869): |url_request_context_| is not configured
-    // correctly in some unittests. We should fix those tests and turn this 'if'
-    // into a DCHECK.
-    if (partition->url_request_context_)
-      partition->url_loader_factory_getter()->HandleFactoryRequests();
+    DCHECK(partition->url_request_context_);
+    partition->url_loader_factory_getter()->HandleFactoryRequests();
   }
 
   PostCreateInitialization(partition, in_memory);

content/public/test/test_browser_context.cc

@@ -173,7 +173,9 @@ TestBrowserContext::CreateRequestContextForStoragePartition(
     ProtocolHandlerMap* protocol_handlers,
     URLRequestInterceptorScopedVector request_interceptors) {
   request_interceptors_ = std::move(request_interceptors);
-  return nullptr;
+  // Simply returns the same RequestContext since no tests is relying on the
+  // expected behavior.
+  return GetRequestContext();
 }
 
 net::URLRequestContextGetter* TestBrowserContext::CreateMediaRequestContext() {