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 e4f4846f67b1e909fa6168de59350f80d62a87f6..9412ab1f059251e87c8009f1dbec5d097bf08b19 100644
--- a/content/test/test_web_contents.cc
+++ b/content/test/test_web_contents.cc
@@ -62,6 +62,11 @@ TestRenderFrameHost* TestWebContents::GetPendingMainFrame() const {
       GetRenderManager()->pending_frame_host());
 }
 
+TestRenderFrameHost* TestWebContents::GetSpeculativeMainFrame() const {
+  return static_cast<TestRenderFrameHost*>(
+      GetRenderManager()->speculative_render_frame_host_.get());
+}
+
 void TestWebContents::TestDidNavigate(RenderFrameHost* render_frame_host,
                                       int page_id,
                                       const GURL& url,
@@ -171,7 +176,14 @@ void TestWebContents::CommitPendingNavigation() {
   // navigate.
   ProceedWithCrossSiteNavigation();
   TestRenderFrameHost* old_rfh = GetMainFrame();
-  TestRenderFrameHost* rfh = GetPendingMainFrame();
+  TestRenderFrameHost* rfh;
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableBrowserSideNavigation)) {
+    rfh = GetSpeculativeMainFrame();

[clamy, 2014/12/19 13:35:57]

This is one of the cases where having a method that returns either the pending
or the speculative RFH would come in handy.

[carlosk, 2014/12/29 16:40:16]

Done.

+  } else {
+    rfh = GetPendingMainFrame();
+  }
+
   if (!rfh)
     rfh = old_rfh;
 
@@ -191,7 +203,11 @@ void TestWebContents::CommitPendingNavigation() {
 }
 
 void TestWebContents::ProceedWithCrossSiteNavigation() {
-  if (!GetPendingMainFrame())
+  // Note: At the moment in the navigation process when this method is called

[nasko, 2014/12/20 00:09:09]

nit: s/process/progress/

[carlosk, 2014/12/29 16:40:17]

(comment was removed)

+  // (after the RenderFrameHost committed), the speculative RenderFrameHost, if

[nasko, 2014/12/20 00:09:09]

"(after the RenderFrameHost committed)" Is this actually true? The fact that the
code later sends the BeforeUnloadACK it means that the navigation hasn't
committed, though it has started.

[carlosk, 2014/12/29 16:40:17]

What I meant was that the call to RFH::CommitNavigation aldready happened (it
happens when we call CallOnResponseStarted on the loader). Is that not what we
mean by the RFH having committed? 

But this comment was removed anyway.

[clamy, 2014/12/29 17:36:21]

In the current code path this function is called before the navigation has even
started. The navigation can only start when the BeforeUnload ack has been
received, which is what the function simulates.

[carlosk, 2014/12/30 15:54:50]

Acknowledged. What I said before was wrong...

+  // any, is already guaranteed to be the one that will be made active. That's
+  // why this works.
+  if (!GetPendingMainFrame() && !GetSpeculativeMainFrame())

[clamy, 2014/12/19 13:35:57]

This function should only be called at the beginning of a cross-site navigation
in the current codepath. In PlzNavigate, the execution of the BeforeUnload
handler is to be done through the RequestNavigation/BeginNavigation pair.

Therefore, what you should do here is return immediately when PlzNavigate is
enabled, or have a DCHECK PlzNavigate is not enabled, and make sure we don't
call it when it is.

[carlosk, 2014/12/29 16:40:17]

Done the 1st option as it eases things.

     return;
   GetMainFrame()->SendBeforeUnloadACK(true);
 }