Make RenderViewHostTestHarness create a net::NetworkChangeNotifier

This makes RenderViewHostTestHarness own a NetworkChangeNotifier,
so Network Service can skip creating one (see
CreateNetworkChangeNotifierIfNeeded() in network_service.cc). The
in-process NetworkService is a leaky global singleton, which also
leaks a NetworkChangeNotifier that conflicts with subsequent unit
tests.

See: https://groups.google.com/a/chromium.org/d/msg/network-service-dev/IgNFrq1zFHI/FNCAplsCCQAJ

An alternative approach is to tear down the in-process singleton
NetworkService, but I ran into issues when doing that mostly because
the BrowserThreadDelegate::CleanUp hook is only implemented by
chrome/browser/io_thread.h and not by other content embedders.

Change-Id: I1fbfca32e582621c3cfcbb7af3a82a4243c5b44b
Reviewed-on: https://chromium-review.googlesource.com/1114924
Commit-Queue: Helen Li <xunjieli@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#571560}

content/public/test/test_renderer_host.cc

@@ -29,6 +29,7 @@
 #include "content/test/test_render_view_host_factory.h"
 #include "content/test/test_render_widget_host_factory.h"
 #include "content/test/test_web_contents.h"
+#include "net/base/network_change_notifier.h"
 #include "ui/base/material_design/material_design_controller.h"
 #include "ui/base/test/material_design_controller_test_api.h"
 
@@ -247,6 +248,12 @@ void RenderViewHostTestHarness::NavigateAndCommit(const GURL& url) {
 }
 
 void RenderViewHostTestHarness::SetUp() {
+  // Create and own a NetworkChangeNotifier so that it will not be created
+  // during the initialization of the global leaky singleton NetworkService. The
+  // global NetworkService's NetworkChangeNotifier can affect subsequent unit
+  // tests.
+  network_change_notifier_.reset(net::NetworkChangeNotifier::CreateMock());
+
   // ContentTestSuiteBase might have already initialized
   // MaterialDesignController in unit_tests suite.
   ui::test::MaterialDesignControllerTestAPI::Uninitialize();

content/public/test/test_renderer_host.h

@@ -34,6 +34,10 @@ namespace display {
 class Screen;
 }
 
+namespace net {
+class NetworkChangeNotifier;
+}
+
 namespace ui {
 class ScopedOleInitializer;
 }
@@ -265,6 +269,8 @@ class RenderViewHostTestHarness : public testing::Test {
  private:
   std::unique_ptr<TestBrowserThreadBundle> thread_bundle_;
 
+  std::unique_ptr<net::NetworkChangeNotifier> network_change_notifier_;
+
   std::unique_ptr<ContentBrowserSanityChecker> sanity_checker_;
 
   std::unique_ptr<BrowserContext> browser_context_;