PlzNavigate: Speculatively spawns a renderer process for navigations.

content/test/test_web_contents.h

Index: content/test/test_web_contents.h
diff --git a/content/test/test_web_contents.h b/content/test/test_web_contents.h
index 8e3c2b55f382e97046ed300a1fbcd5cd4df6e19a..886e337e1a18a65e3a9ab67cf72e9bd3fe9d1341 100644
--- a/content/test/test_web_contents.h
+++ b/content/test/test_web_contents.h
@@ -94,6 +94,13 @@ class TestWebContents : public WebContentsImpl, public WebContentsTester {
                                 int error_code,
                                 const base::string16& error_description);
 
+  // PlzNavigate
+  // When running in regular mode returns the same result as a call to
+  // GetPendingMainFrame. When browser side navigation is enabled it returns the
+  // speculative RenderFrameHost for the main frame if one exists. Otherwise
+  // returns nullptr.
+  TestRenderFrameHost* GetNextMainFrameCandidate() const;
+
  protected:
   // The deprecated WebContentsTester still needs to subclass this.
   explicit TestWebContents(BrowserContext* browser_context);