[Chromecast] Get secure DevTools browser target URL

This reverts exposing the browser target unconditionally; the proper
solution is to retrieve the secure browser target URL from
/json/version server endpoint.

Bug: internal b/65209777
Change-Id: I0b77c7bb39a06cc19fc6fac68f341aded8cdd154
Reviewed-on: https://chromium-review.googlesource.com/663892Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Commit-Queue: Sean Topping <seantopping@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501462}

chromecast/browser/devtools/cast_devtools_manager_delegate.cc

@@ -67,9 +67,5 @@ std::string CastDevToolsManagerDelegate::GetDiscoveryPageHTML() {
 #endif
 }
 
-bool CastDevToolsManagerDelegate::IsBrowserTargetDiscoverable() {
-  return true;
-}
-
 }  // namespace shell
 }  // namespace chromecast

chromecast/browser/devtools/cast_devtools_manager_delegate.h

@@ -34,7 +34,6 @@ class CastDevToolsManagerDelegate : public content::DevToolsManagerDelegate {
   // content::DevToolsManagerDelegate implementation.
   content::DevToolsAgentHost::List RemoteDebuggingTargets() override;
   std::string GetDiscoveryPageHTML() override;
-  bool IsBrowserTargetDiscoverable() override;
 
  private:
   std::unordered_set<content::WebContents*> enabled_webcontents_;

chromecast/browser/devtools/remote_debugging_server.cc

@@ -174,6 +174,10 @@ void RemoteDebuggingServer::DisableWebContentsForDebugging(
   dev_tools_delegate->DisableWebContentsForDebugging(web_contents);
 
   if (is_started_ && !dev_tools_delegate->HasEnabledWebContents()) {
+    // TODO(seantopping): The debugging server goes down temporarily when there
+    // are no active apps. This can sometimes break in-progress traces. Find a
+    // fix for this.
+    LOG(INFO) << "Stopping Devtools server.";
     content::DevToolsAgentHost::StopRemoteDebuggingServer();
     is_started_ = false;
   }

chromecast/tools/tracinglib.py

@@ -8,6 +8,7 @@
 import json
 import logging
 import math
+import requests
 import subprocess
 import time
 import websocket
@@ -44,7 +45,10 @@ class TracingBackend(object):
   def Connect(self):
     """Connect to cast_shell."""
     assert not self._socket
-    url = 'ws://%s:%i/devtools/browser' % (self._device_ip, self._devtools_port)
+    # Get the secure browser debugging target.
+    r = requests.get(
+        'http://%s:%i/json/version' % (self._device_ip, self._devtools_port))
+    url = r.json()['webSocketDebuggerUrl']
     print('Connect to %s ...' % url)
     self._socket = websocket.create_connection(url, timeout=self._timeout)
     self._next_request_id = 0