Pipe the devTools FrameId from blink into the browser for headless

content/browser/devtools/devtools_agent_host_impl.cc

Index: content/browser/devtools/devtools_agent_host_impl.cc
diff --git a/content/browser/devtools/devtools_agent_host_impl.cc b/content/browser/devtools/devtools_agent_host_impl.cc
index a23f00b5667a78b75d9b899a6b6392ed057bb703..2f52d8f5ef9d5131335efc1261c656b0c0eba044 100644
--- a/content/browser/devtools/devtools_agent_host_impl.cc
+++ b/content/browser/devtools/devtools_agent_host_impl.cc
@@ -21,6 +21,7 @@
 #include "content/browser/devtools/service_worker_devtools_manager.h"
 #include "content/browser/devtools/shared_worker_devtools_agent_host.h"
 #include "content/browser/devtools/shared_worker_devtools_manager.h"
+#include "content/browser/frame_host/frame_tree_node.h"
 #include "content/browser/loader/netlog_observer.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/content_browser_client.h"
@@ -58,6 +59,16 @@ bool DevToolsAgentHost::IsSupportedProtocolVersion(const std::string& version) {
 }
 
 // static
+std::string DevToolsAgentHost::GetDevToolsFrameIdForFrameTreeNodeId(
+    int frame_tree_node_id) {

[Charlie Reis, 2017/04/24 20:26:42]

We've been talking about how to make APIs like this safer, since it's too easy
at the moment to introduce security bugs this way.  The FTN ID doesn't change
even when a cross-process navigation has taken place (e.g., between
chrome://settings and evil.com), so you might be getting a string here that was
sent up from a compromised renderer process when expecting one for a highly
privileged page.

One way to make it safer is to require the caller to pass in a process ID any
time they pass in a FrameTreeNode ID, so we can check that it agrees with the
current_frame_host's process inside this call.

[alex clarke (OOO till 29th), 2017/04/25 15:01:03]

Done.

[Charlie Reis, 2017/04/26 19:52:55]

Thanks!

+  FrameTreeNode* frame_tree_node =
+      FrameTreeNode::GloballyFindByID(frame_tree_node_id);
+  if (!frame_tree_node)
+    return "";
+  return frame_tree_node->current_frame_host()->devtools_frame_id();
+}
+
+// static
 DevToolsAgentHost::List DevToolsAgentHost::GetOrCreateAll() {
   List result;
   SharedWorkerDevToolsAgentHost::List shared_list;