Reduce/remove usage of BrowserThread in content/browser/loader.

content/browser/loader/resource_dispatcher_host_unittest.cc

Index: content/browser/loader/resource_dispatcher_host_unittest.cc
diff --git a/content/browser/loader/resource_dispatcher_host_unittest.cc b/content/browser/loader/resource_dispatcher_host_unittest.cc
index aff0952bcce9f98ca39facfada6f3eec34e52f44..3ae0718c9f7e9fc6701277d75959fca0e35cf453 100644
--- a/content/browser/loader/resource_dispatcher_host_unittest.cc
+++ b/content/browser/loader/resource_dispatcher_host_unittest.cc
@@ -257,7 +257,8 @@ class TestFilterSpecifyingChild : public ResourceMessageFilter {
             NULL,
             NULL,
             base::Bind(&TestFilterSpecifyingChild::GetContexts,
-                       base::Unretained(this))),
+                       base::Unretained(this)),
+            BrowserThread::GetTaskRunnerForThread(BrowserThread::IO)),
         resource_context_(resource_context),
         canceled_(false),
         received_after_canceled_(0) {
@@ -848,7 +849,8 @@ class ResourceDispatcherHostTest : public testing::Test, public IPC::Sender {
 
   ResourceDispatcherHostTest()
       : thread_bundle_(content::TestBrowserThreadBundle::IO_MAINLOOP),
-        host_(base::Bind(&DownloadResourceHandler::Create)),
+        host_(base::Bind(&DownloadResourceHandler::Create),
+              base::ThreadTaskRunnerHandle::Get()),
         use_test_ssl_certificate_(false),
         send_data_received_acks_(false),
         auto_advance_(false) {
@@ -867,6 +869,8 @@ class ResourceDispatcherHostTest : public testing::Test, public IPC::Sender {
 
   ~ResourceDispatcherHostTest() override {
     filter_->OnChannelClosing();
+    filter_ = nullptr;
+    web_contents_filter_ = nullptr;
   }
 
   // IPC::Sender implementation