[DevTools] Migrate from AgentStateCallbacks to DevToolsAgentHostObserver.

extensions/browser/app_window/app_window_registry.cc

Index: extensions/browser/app_window/app_window_registry.cc
diff --git a/extensions/browser/app_window/app_window_registry.cc b/extensions/browser/app_window/app_window_registry.cc
index 6fc0dedccfabd7cb140f09bdbd72a3a79e94435e..b9c9f1d10cfbf17835ae98572ba808812caf2037 100644
--- a/extensions/browser/app_window/app_window_registry.cc
+++ b/extensions/browser/app_window/app_window_registry.cc
@@ -45,14 +45,12 @@ AppWindowRegistry::Observer::~Observer() {
 }
 
 AppWindowRegistry::AppWindowRegistry(content::BrowserContext* context)
-    : context_(context),
-      devtools_callback_(base::Bind(&AppWindowRegistry::OnDevToolsStateChanged,
-                                    base::Unretained(this))) {
-  content::DevToolsAgentHost::AddAgentStateCallback(devtools_callback_);
+    : context_(context) {
+  content::DevToolsAgentHost::AddObserver(this);
 }
 
 AppWindowRegistry::~AppWindowRegistry() {
-  content::DevToolsAgentHost::RemoveAgentStateCallback(devtools_callback_);
+  content::DevToolsAgentHost::RemoveObserver(this);
 }
 
 // static
@@ -180,21 +178,17 @@ bool AppWindowRegistry::HadDevToolsAttached(
   return key.empty() ? false : inspected_windows_.count(key) != 0;
 }
 
-void AppWindowRegistry::OnDevToolsStateChanged(
-    content::DevToolsAgentHost* agent_host,
-    bool attached) {
-  content::WebContents* web_contents = agent_host->GetWebContents();
-  // Ignore unrelated notifications.
-  if (!web_contents || web_contents->GetBrowserContext() != context_)
-    return;
-
-  std::string key = GetWindowKeyForWebContents(web_contents);
-  if (key.empty())
-    return;
-
-  if (attached)
+void AppWindowRegistry::DevToolsAgentHostAttached(
+    content::DevToolsAgentHost* agent_host) {
+  std::string key = GetWindowKeyForAgentHost(agent_host);
+  if (!key.empty())
     inspected_windows_.insert(key);
-  else
+}
+
+void AppWindowRegistry::DevToolsAgentHostDetached(
+    content::DevToolsAgentHost* agent_host) {
+  std::string key = GetWindowKeyForAgentHost(agent_host);
+  if (!key.empty())
     inspected_windows_.erase(key);
 }
 
@@ -214,6 +208,14 @@ void AppWindowRegistry::BringToFront(AppWindow* app_window) {
   app_windows_.push_front(app_window);
 }
 
+std::string AppWindowRegistry::GetWindowKeyForAgentHost(
+    content::DevToolsAgentHost* agent_host) const {
+  content::WebContents* web_contents = agent_host->GetWebContents();
+  if (!web_contents || web_contents->GetBrowserContext() != context_)
+    return std::string();
+  return GetWindowKeyForWebContents(web_contents);
+}
+
 std::string AppWindowRegistry::GetWindowKeyForWebContents(
     content::WebContents* web_contents) const {
   AppWindow* app_window = GetAppWindowForWebContents(web_contents);