Avoid using BrowserThread and ContentBrowserClient in NetLogObserver.

content/browser/devtools/devtools_manager.cc

Index: content/browser/devtools/devtools_manager.cc
diff --git a/content/browser/devtools/devtools_manager.cc b/content/browser/devtools/devtools_manager.cc
index f3004a3e7e721fa1ddd3cb0083219b31272b5a49..92b3b04031d2a367e85919416322cfe7fc1574f2 100644
--- a/content/browser/devtools/devtools_manager.cc
+++ b/content/browser/devtools/devtools_manager.cc
@@ -21,6 +21,9 @@ DevToolsManager* DevToolsManager::GetInstance() {
 DevToolsManager::DevToolsManager()
     : delegate_(GetContentClient()->browser()->GetDevToolsManagerDelegate()),
       attached_hosts_count_(0) {
+  // Pass the IO thread task runner to the NetLogObserver class.
+  NetLogObserver::SetIOThreadTaskRunner(

[pfeldman, 2016/07/06 18:36:14]

It is unclear why netlog observer is initialized with the thread from the
devtools manager. The scope of netlog is greater than the one of the manager.

[ananta, 2016/07/08 14:11:02]

Passed it via Attach instead.

+      BrowserThread::GetMessageLoopProxyForThread(BrowserThread::IO));
 }
 
 DevToolsManager::~DevToolsManager() {
@@ -34,7 +37,8 @@ void DevToolsManager::AgentHostStateChanged(
       BrowserThread::PostTask(
           BrowserThread::IO,
           FROM_HERE,
-          base::Bind(&NetLogObserver::Attach));
+          base::Bind(&NetLogObserver::Attach,
+                     GetContentClient()->browser()->GetNetLog()));
     }
     ++attached_hosts_count_;
   } else {