Port BatteryMonitor into Device Service

content/browser/browser_main_loop.cc

Index: content/browser/browser_main_loop.cc
diff --git a/content/browser/browser_main_loop.cc b/content/browser/browser_main_loop.cc
index d6d917b4c3f3ac7a90f23333b621bec4cf94a67f..c7d97015d391925bdc9e0a95470ce2cb6269fedd 100644
--- a/content/browser/browser_main_loop.cc
+++ b/content/browser/browser_main_loop.cc
@@ -90,7 +90,6 @@
 #include "content/public/common/content_switches.h"
 #include "content/public/common/main_function_params.h"
 #include "content/public/common/result_codes.h"
-#include "device/battery/battery_status_service.h"
 #include "device/gamepad/gamepad_service.h"
 #include "media/base/media.h"
 #include "media/base/user_input_monitor.h"
@@ -1366,12 +1365,6 @@ void BrowserMainLoop::ShutdownThreadsAndCleanUp() {
     TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:SensorService");
     DeviceSensorService::GetInstance()->Shutdown();
   }
-#if !defined(OS_ANDROID)
-  {
-    TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:BatteryStatusService");
-    device::BatteryStatusService::GetInstance()->Shutdown();

[blundell, 2017/01/24 11:35:43]

As I wrote in the CL description, the move of this call to the Device Service
destructor has the effect of having this code execute earlier in this method, at
line 1259 (ServiceManagerContext's destructor calls
ServiceManagerConnection::DestroyForProcess(), which destroys the
ServiceManagerConnectionImpl that the Device Service was added to, which causes
the Device Service to be destroyed). From looking at
BatteryStatusService::Shutdown(), I don't see any problem with this move. Tim,
do you? 

[timvolodine, 2017/01/27 18:16:27]

hmm I am somewhat concerned that this would happen before ipc shutdown which
would be different from the current logic. Are you sure we won't hit 
DCHECK(!is_shutdown_) in AddCallback if such a call comes in after
BatteryStatusService::Shutdown ?

-  }
-#endif
   {
     TRACE_EVENT0("shutdown", "BrowserMainLoop::Subsystem:DeleteDataSources");
     URLDataManager::DeleteDataSources();