[Chromecast] Add CreateWebView() method to CastBrowserTest

Allow CastWebView to be created and WebContents retrieved so that a
WebContentsObserver can be added before navigating to the URL.

Bug: internal b/73180315
Test: cast_shell_internal_browsertests
Change-Id: I0c47b5f3c1dca4fe9384c6675b3edf6acd51c793
Reviewed-on: https://chromium-review.googlesource.com/923714Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Commit-Queue: James West <jameswest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537493}

chromecast/browser/test/cast_browser_test.cc

@@ -52,7 +52,7 @@ void CastBrowserTest::PostRunTestOnMainThread() {
   cast_web_view_.reset();
 }
 
-content::WebContents* CastBrowserTest::NavigateToURL(const GURL& url) {
+content::WebContents* CastBrowserTest::CreateWebView() {
   CastWebView::CreateParams params;
   params.delegate = this;
   params.enabled_for_dev = true;
@@ -61,7 +61,13 @@ content::WebContents* CastBrowserTest::NavigateToURL(const GURL& url) {
                                            nullptr,         /* extension */
                                            GURL() /* initial_url */);
 
-  content::WebContents* web_contents = cast_web_view_->web_contents();
+  return cast_web_view_->web_contents();
+}
+
+content::WebContents* CastBrowserTest::NavigateToURL(const GURL& url) {
+  content::WebContents* web_contents =
+      cast_web_view_ ? cast_web_view_->web_contents() : CreateWebView();
+
   content::WaitForLoadStop(web_contents);
   content::TestNavigationObserver same_tab_observer(web_contents, 1);
 

chromecast/browser/test/cast_browser_test.h

@@ -38,6 +38,7 @@ class CastBrowserTest : public content::BrowserTestBase, CastWebView::Delegate {
   void PreRunTestOnMainThread() override;
   void PostRunTestOnMainThread() override;
 
+  content::WebContents* CreateWebView();
   content::WebContents* NavigateToURL(const GURL& url);
 
  private: