Add UMA metric: Startup.BrowserMainToRendererMain.

components/startup_metric_utils/common/startup_metric_message_generator.cc

Index: components/startup_metric_utils/common/startup_metric_message_generator.cc
diff --git a/components/guest_view/common/guest_view_message_generator.cc b/components/startup_metric_utils/common/startup_metric_message_generator.cc
similarity index 58%
copy from components/guest_view/common/guest_view_message_generator.cc
copy to components/startup_metric_utils/common/startup_metric_message_generator.cc
index 6a0bca159e1ae477e6c4f61c8f6effcb7e03acb5..dbd429cc51bea2740bcf17bdcbe1474929abb59f 100644
--- a/components/guest_view/common/guest_view_message_generator.cc
+++ b/components/startup_metric_utils/common/startup_metric_message_generator.cc
@@ -4,30 +4,30 @@
 
 // Get basic type definitions.
 #define IPC_MESSAGE_IMPL
-#include "components/guest_view/common/guest_view_message_generator.h"
+#include "components/startup_metric_utils/common/startup_metric_message_generator.h"
 
 // Generate constructors.
 #include "ipc/struct_constructor_macros.h"
-#include "components/guest_view/common/guest_view_message_generator.h"
+#include "components/startup_metric_utils/common/startup_metric_message_generator.h"
 
 // Generate destructors.
 #include "ipc/struct_destructor_macros.h"
-#include "components/guest_view/common/guest_view_message_generator.h"
+#include "components/startup_metric_utils/common/startup_metric_message_generator.h"
 
 // Generate param traits write methods.
 #include "ipc/param_traits_write_macros.h"
 namespace IPC {
-#include "components/guest_view/common/guest_view_message_generator.h"
+#include "components/startup_metric_utils/common/startup_metric_message_generator.h"
 }  // namespace IPC
 
 // Generate param traits read methods.
 #include "ipc/param_traits_read_macros.h"
 namespace IPC {
-#include "components/guest_view/common/guest_view_message_generator.h"
+#include "components/startup_metric_utils/common/startup_metric_message_generator.h"
 }  // namespace IPC
 
 // Generate param traits log methods.
 #include "ipc/param_traits_log_macros.h"
 namespace IPC {
-#include "components/guest_view/common/guest_view_message_generator.h"
+#include "components/startup_metric_utils/common/startup_metric_message_generator.h"
 }  // namespace IPC