[PowerProfiler] Power profiler service keeps running even after devtools frontend has been closed.

content/browser/devtools/devtools_power_handler.cc

Index: content/browser/devtools/devtools_power_handler.cc
diff --git a/content/browser/devtools/devtools_power_handler.cc b/content/browser/devtools/devtools_power_handler.cc
index 43772b47607e2dddd54bd4cab003f3f8f5716e3d..1eb4edd0a8bec19d6ef2fb90cf5746158861ffaa 100644
--- a/content/browser/devtools/devtools_power_handler.cc
+++ b/content/browser/devtools/devtools_power_handler.cc
@@ -8,10 +8,16 @@
 #include "base/values.h"
 #include "content/browser/devtools/devtools_protocol_constants.h"
 #include "content/browser/power_profiler/power_profiler_service.h"
+#include "content/public/browser/devtools_manager.h"
 
 namespace content {
 
-DevToolsPowerHandler::DevToolsPowerHandler() {
+DevToolsPowerHandler::DevToolsPowerHandler(
+    DevToolsAgentHost* devtools_agent_host)
+    : devtools_agent_host_(devtools_agent_host),
+      devtools_callback_(
+          base::Bind(&DevToolsPowerHandler::OnDevToolsStateChanged,
+                     base::Unretained(this))) {
   RegisterCommandHandler(devtools::Power::start::kName,
                          base::Bind(&DevToolsPowerHandler::OnStart,
                                     base::Unretained(this)));
@@ -21,10 +27,14 @@ DevToolsPowerHandler::DevToolsPowerHandler() {
   RegisterCommandHandler(devtools::Power::canProfilePower::kName,
                          base::Bind(&DevToolsPowerHandler::OnCanProfilePower,
                                     base::Unretained(this)));
+  content::DevToolsManager::GetInstance()->AddAgentStateCallback(
+      devtools_callback_);
 }
 
 DevToolsPowerHandler::~DevToolsPowerHandler() {
   PowerProfilerService::GetInstance()->RemoveObserver(this);
+  content::DevToolsManager::GetInstance()->RemoveAgentStateCallback(
+      devtools_callback_);
 }
 
 void DevToolsPowerHandler::OnPowerEvent(const PowerEventVector& events) {
@@ -80,4 +90,12 @@ DevToolsPowerHandler::OnCanProfilePower(
   return command->SuccessResponse(result);
 }
 
+void DevToolsPowerHandler::OnDevToolsStateChanged(
+    content::DevToolsAgentHost* agent_host,
+    bool attached) {
+  if (!attached && agent_host == devtools_agent_host_) {
+    PowerProfilerService::GetInstance()->RemoveObserver(this);
+  }
+}
+
 }  // namespace content