Fix front-end host creation upon navigation

content/browser/devtools/devtools_frontend_host_impl.cc

Index: content/browser/devtools/devtools_frontend_host_impl.cc
diff --git a/content/browser/devtools/devtools_frontend_host_impl.cc b/content/browser/devtools/devtools_frontend_host_impl.cc
index 9c101d26b87b0b542c74f372d72dd6820a6262a0..1d4aa95bf61a3def529392d98b873561d5d1eb6c 100644
--- a/content/browser/devtools/devtools_frontend_host_impl.cc
+++ b/content/browser/devtools/devtools_frontend_host_impl.cc
@@ -7,6 +7,8 @@
 #include <stddef.h>
 
 #include "content/browser/bad_message.h"
+#include "content/browser/frame_host/frame_tree.h"
+#include "content/browser/web_contents/web_contents_impl.h"
 #include "content/common/devtools_messages.h"
 #include "content/public/browser/navigation_entry.h"
 #include "content/public/browser/render_frame_host.h"
@@ -25,9 +27,13 @@ const char kCompatibilityScriptSourceURL[] =
 
 // static
 DevToolsFrontendHost* DevToolsFrontendHost::Create(
-    RenderFrameHost* frontend_main_frame,
+    WebContents* web_contents,
     const HandleMessageCallback& handle_message_callback) {
-  return new DevToolsFrontendHostImpl(frontend_main_frame,
+  RenderFrameHost* frame = web_contents->GetMainFrame();
+  FrameTree* tree = static_cast<WebContentsImpl*>(web_contents)->GetFrameTree();
+  RenderFrameHostManager* rfhm = tree->root()->render_manager();
+  RenderFrameHost* pending_frame = rfhm->pending_frame_host();
+  return new DevToolsFrontendHostImpl(pending_frame ? pending_frame : frame,

[pfeldman, 2017/01/10 22:31:51]

This looks fragile and implementation implies navigation is racy. Can we always
use pending host from the call site?

                                       handle_message_callback);
 }