Network Service: Use web::TestWebThreadBundle in the NetworkMetricsProviderTest

This is a follow-up CL from the comments at:
https://chromium-review.googlesource.com/c/chromium/src/+/1274585/11

This CL uses ifdef "using" decl to use web::TestWebThreadBundle on iOS as
the equivalent to content::TestBrowserThreadBundle.

Bug: 898307
Change-Id: I35620aade68dc2b6e9855be49afabd5fcd6dfd5d
Reviewed-on: https://chromium-review.googlesource.com/c/1313450Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Commit-Queue: Jun Cai <juncai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609382}

components/metrics/BUILD.gn

@@ -431,6 +431,10 @@ source_set("unit_tests") {
     sources -= [ "child_call_stack_profile_collector_unittest.cc" ]
   }
 
+  if (is_ios) {
+    deps += [ "//ios/web/public/test" ]
+  }
+
   if (!is_ios) {
     deps += [ "//content/test:test_support" ]
   }

components/metrics/net/DEPS

@@ -5,6 +5,7 @@ include_rules = [
   "+components/encrypted_messages",
   "+components/variations",
   "+content/public/test/test_browser_thread_bundle.h",
+  "+ios/web/public/test/test_web_thread_bundle.h",
   "+net",
   "+services/network/public/cpp",
   "+services/network/test",

components/metrics/net/network_metrics_provider_unittest.cc

@@ -22,9 +22,11 @@
 #endif  // OS_CHROMEOS
 
 #if defined(OS_IOS)
-#include "base/test/scoped_task_environment.h"
+#include "ios/web/public/test/test_web_thread_bundle.h"
+using TestThreadBundle = web::TestWebThreadBundle;
 #else  // !defined(OS_IOS)
 #include "content/public/test/test_browser_thread_bundle.h"
+using TestThreadBundle = content::TestBrowserThreadBundle;
 #endif  // defined(OS_IOS)
 
 namespace metrics {
@@ -33,14 +35,7 @@ class NetworkMetricsProviderTest : public testing::Test {
  public:
  protected:
   NetworkMetricsProviderTest()
-#if defined(OS_IOS)
-      : scoped_task_environment_(
-            base::test::ScopedTaskEnvironment::MainThreadType::IO)
-#else   // !defined(OS_IOS)
-      : test_browser_thread_bundle_(
-            content::TestBrowserThreadBundle::IO_MAINLOOP)
-#endif  // defined(OS_IOS)
-  {
+      : test_thread_bundle_(TestThreadBundle::IO_MAINLOOP) {
 #if defined(OS_CHROMEOS)
     chromeos::DBusThreadManager::Initialize();
     chromeos::NetworkHandler::Initialize();
@@ -48,11 +43,7 @@ class NetworkMetricsProviderTest : public testing::Test {
   }
 
  private:
-#if defined(OS_IOS)
-  base::test::ScopedTaskEnvironment scoped_task_environment_;
-#else   // !defined(OS_IOS)
-  content::TestBrowserThreadBundle test_browser_thread_bundle_;
-#endif  // defined(OS_IOS)
+  TestThreadBundle test_thread_bundle_;
 };
 
 // Verifies that the effective connection type is correctly set.