Implement the gamepad API in the IPC proxy

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 c9a409a84366080919510b2baa62585c25cd27a8..fd67b56b58740e8999654cb2a8e1141a3dcb6d1a 100644
--- a/content/browser/browser_main_loop.cc
+++ b/content/browser/browser_main_loop.cc
@@ -507,8 +507,6 @@ void BrowserMainLoop::ShutdownThreadsAndCleanUp() {
 #endif
   BrowserGpuChannelHostFactory::Terminate();
 
-  GamepadService::GetInstance()->Terminate();
-
   // The device monitors are using |system_monitor_| as dependency, so delete
   // them before |system_monitor_| goes away.
   // On Mac and windows, the monitor needs to be destroyed on the same thread
@@ -608,6 +606,10 @@ void BrowserMainLoop::ShutdownThreadsAndCleanUp() {
   // more head start for those operations to finish.
   BrowserThreadImpl::ShutdownThreadPool();
 
+  // Must happen after the I/O thread is shutdown since this class lives on the
+  // I/O thread and isn't threadsafe.
+  GamepadService::GetInstance()->Terminate();
+
   if (parts_.get())
     parts_->PostDestroyThreads();
 }