PlzNavigate: Add tests to check WebUI navigations.

content/browser/frame_host/render_frame_host_manager.cc

Index: content/browser/frame_host/render_frame_host_manager.cc
diff --git a/content/browser/frame_host/render_frame_host_manager.cc b/content/browser/frame_host/render_frame_host_manager.cc
index 612868ecc20d6f8dde95c092e9849d5acc81b5fd..17b5b634448bc56cf45bf4348eda7e9ec66f6cfd 100644
--- a/content/browser/frame_host/render_frame_host_manager.cc
+++ b/content/browser/frame_host/render_frame_host_manager.cc
@@ -1000,7 +1000,14 @@ RenderFrameHostImpl* RenderFrameHostManager::GetFrameHostForNavigation(
     // Reuse the current RFH if its SiteInstance matches the the navigation's
     // or if this is a subframe navigation. We only swap RFHs for subframes when
     // --site-per-process is enabled.
-    CleanUpNavigation();
+
+    // There might be a pending WebUI in the current RenderFrameHost from a
+    // previous call of this function in the same navigation and it should be
+    // maintained for the next call to UpdatePendingWebUI. So instead of calling

[clamy, 2015/10/22 16:51:39]

nit: RenderFrameHostImpl::UpdatePendingWebUI.

[carlosk, 2015/10/26 10:33:23]

Done.

+    // CleanUpNavigation, only the speculative RenderFrameHost is discarded.

[clamy, 2015/10/22 16:51:39]

nit: s/the speculative RenderFrameHost is discarded/discard the speculative
RenderFrameHost

[carlosk, 2015/10/26 10:33:23]

Done.

+    if (speculative_render_frame_host_)
+      DiscardUnusedFrame(UnsetSpeculativeRenderFrameHost());
+
     navigation_rfh = render_frame_host_.get();
 
     // As SiteInstances are the same, make the RFH update its possible pending
@@ -1092,8 +1099,6 @@ RenderFrameHostImpl* RenderFrameHostManager::GetFrameHostForNavigation(
 void RenderFrameHostManager::CleanUpNavigation() {
   CHECK(base::CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kEnableBrowserSideNavigation));
-  // TODO(carlosk): the discarding of the current RFH WebUI and the cleanup of
-  // the speculative RFH should not always happen together.
   render_frame_host_->DiscardPendingWebUI();
   if (speculative_render_frame_host_)
     DiscardUnusedFrame(UnsetSpeculativeRenderFrameHost());