Explicitly initialize secondary renderers for layout tests.

content/shell/renderer/layout_test/layout_test_content_renderer_client.cc

Index: content/shell/renderer/layout_test/layout_test_content_renderer_client.cc
diff --git a/content/shell/renderer/layout_test/layout_test_content_renderer_client.cc b/content/shell/renderer/layout_test/layout_test_content_renderer_client.cc
index 526d2d95581f8bbc13a8c156045f924cc5a1a0f5..7f065455a025e694a64ed2c7952ebb1b8a667a30 100644
--- a/content/shell/renderer/layout_test/layout_test_content_renderer_client.cc
+++ b/content/shell/renderer/layout_test/layout_test_content_renderer_client.cc
@@ -111,8 +111,15 @@ void LayoutTestContentRendererClient::RenderViewCreated(
 
   test_runner::WebTestDelegate* delegate =
       LayoutTestRenderProcessObserver::GetInstance()->test_delegate();
-  if (delegate == static_cast<test_runner::WebTestDelegate*>(test_runner))
-    LayoutTestRenderProcessObserver::GetInstance()->SetMainWindow(render_view);
+  if (delegate == static_cast<test_runner::WebTestDelegate*>(test_runner)) {
+    // TODO(lukasza): Should this instead by done by BlinkTestRunner,
+    // when it gets notified by the browser that it is the main window?

[Łukasz Anforowicz, 2016/04/15 20:15:29]

This "todo" should be a long-term goal, but doing it today would introduce
(accidental) test failures, because this changes PrintMessage's behavior by
routing it through a different TestRunner::delegate_ (possibly swapped-out
and/or possible not listened to on the browser side).  Changing PrintMessage to
go through process/control message is tricky as discussed some time ago over
email.

+
+    // Let test_runner layer know what is the main test window.
+    LayoutTestRenderProcessObserver::GetInstance()
+        ->test_interfaces()
+        ->SetWebView(render_view->GetWebView(), proxy);

[Łukasz Anforowicz, 2016/04/15 20:15:29]

This just inlines what used to be in
LayoutTestRenderProcessObserver::SetMainWindow

+  }
 }
 
 WebMediaStreamCenter*