Replace FOR_EACH_OBSERVER in c/b/chromeos with range-based for

chrome/browser/chromeos/drive/drive_integration_service.cc

Index: chrome/browser/chromeos/drive/drive_integration_service.cc
diff --git a/chrome/browser/chromeos/drive/drive_integration_service.cc b/chrome/browser/chromeos/drive/drive_integration_service.cc
index be83492bcacfe385c3c10d6815a7e116a253a9e1..73e2e85efe35b2947cb70fd9b3877227373da7ee 100644
--- a/chrome/browser/chromeos/drive/drive_integration_service.cc
+++ b/chrome/browser/chromeos/drive/drive_integration_service.cc
@@ -465,8 +465,8 @@ void DriveIntegrationService::AddDriveMountPoint() {
 
   if (success) {
     logger_->Log(logging::LOG_INFO, "Drive mount point is added");
-    FOR_EACH_OBSERVER(DriveIntegrationServiceObserver, observers_,
-                      OnFileSystemMounted());
+    for (auto& observer : observers_)
+      observer.OnFileSystemMounted();
   }
 }
 
@@ -476,8 +476,8 @@ void DriveIntegrationService::RemoveDriveMountPoint() {
   if (!mount_point_name_.empty()) {
     job_list()->CancelAllJobs();
 
-    FOR_EACH_OBSERVER(DriveIntegrationServiceObserver, observers_,
-                      OnFileSystemBeingUnmounted());
+    for (auto& observer : observers_)
+      observer.OnFileSystemBeingUnmounted();
 
     storage::ExternalMountPoints* const mount_points =
         storage::ExternalMountPoints::GetSystemInstance();