PlzNavigate: Speculatively spawns a renderer process for navigations.

content/test/test_web_contents.cc

Index: content/test/test_web_contents.cc
diff --git a/content/test/test_web_contents.cc b/content/test/test_web_contents.cc
index 6a2e05e2b9cc805bcd8109b20f72f186841f8c35..95b9688b59a0fe2edf4dfe3740a55d1d61f79521 100644
--- a/content/test/test_web_contents.cc
+++ b/content/test/test_web_contents.cc
@@ -55,6 +55,11 @@ TestRenderViewHost* TestWebContents::GetRenderViewHost() const {
 }
 
 TestRenderFrameHost* TestWebContents::GetPendingMainFrame() const {
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableBrowserSideNavigation)) {
+    return static_cast<TestRenderFrameHost*>(
+        GetRenderManager()->speculative_render_frame_host_.get());
+  }
   return static_cast<TestRenderFrameHost*>(
       GetRenderManager()->pending_frame_host());
 }