mash: Exit the root process if the window manager service crashes

services/service_manager/background/background_service_manager.cc

Index: services/service_manager/background/background_service_manager.cc
diff --git a/services/service_manager/background/background_service_manager.cc b/services/service_manager/background/background_service_manager.cc
index 09b2e86403d2aac3c3e72664e8578fe06a374450..d74a8a61b34d032446aa9d7b984a8a513f4fbae3 100644
--- a/services/service_manager/background/background_service_manager.cc
+++ b/services/service_manager/background/background_service_manager.cc
@@ -25,6 +25,19 @@
 #include "services/service_manager/standalone/context.h"
 
 namespace service_manager {
+namespace {
+
+// Calls |callback| on |callback_task_runner|'s thread.
+void CallCallbackWithIdentity(
+    const scoped_refptr<base::TaskRunner> callback_task_runner,
+    const base::Callback<void(const Identity&)>& callback,
+    const Identity& identity) {
+  DCHECK(callback);
+  DCHECK(identity.IsValid());
+  callback_task_runner->PostTask(FROM_HERE, base::Bind(callback, identity));
+}
+
+}  // namespace
 
 BackgroundServiceManager::BackgroundServiceManager(
     service_manager::ServiceProcessLauncher::Delegate* launcher_delegate,
@@ -62,6 +75,29 @@ void BackgroundServiceManager::RegisterService(
                  base::Passed(&pid_receiver_request)));
 }
 
+void BackgroundServiceManager::SetInstanceQuitCallback(
+    base::Callback<void(const Identity&)> callback) {
+  DCHECK(callback);
+  // Hop to the background thread. The provided callback will be called on
+  // whichever thread called this function.
+  background_thread_.task_runner()->PostTask(
+      FROM_HERE,
+      base::Bind(
+          &BackgroundServiceManager::SetInstanceQuitCallbackOnBackgroundThread,
+          base::Unretained(this), base::ThreadTaskRunnerHandle::Get(),
+          callback));
+}
+
+void BackgroundServiceManager::SetInstanceQuitCallbackOnBackgroundThread(
+    const scoped_refptr<base::SingleThreadTaskRunner>& callback_task_runner,
+    const base::Callback<void(const Identity&)>& callback) {
+  DCHECK(callback_task_runner);
+  DCHECK(callback);
+  // Calls |callback| with the identity of the service that is quitting.
+  context_->service_manager()->SetInstanceQuitCallback(
+      base::Bind(&CallCallbackWithIdentity, callback_task_runner, callback));
+}
+
 void BackgroundServiceManager::InitializeOnBackgroundThread(
     service_manager::ServiceProcessLauncher::Delegate* launcher_delegate,
     std::unique_ptr<base::Value> catalog_contents) {