Split FatalCrashEventsObserver to multiple files

Split FatalCrashEventsObserver to multiple files, one for itself and one
for each nested class.

Bug: b:266018440
Change-Id: Id71ca2d59c9f1eb09ed927b2114116832878dd3d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4960473
Reviewed-by: Vignesh Shenvi <vshenvi@google.com>
Commit-Queue: Hong Xu <xuhong@google.com>
Reviewed-by: Leonid Baraz <lbaraz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1213103}

chrome/browser/ash/BUILD.gn

@@ -2659,6 +2659,10 @@ source_set("ash") {
     "policy/reporting/metrics_reporting/device_activity/device_activity_sampler.h",
     "policy/reporting/metrics_reporting/fatal_crash/fatal_crash_events_observer.cc",
     "policy/reporting/metrics_reporting/fatal_crash/fatal_crash_events_observer.h",
+    "policy/reporting/metrics_reporting/fatal_crash/fatal_crash_events_observer_reported_local_id_manager.cc",
+    "policy/reporting/metrics_reporting/fatal_crash/fatal_crash_events_observer_reported_local_id_manager.h",
+    "policy/reporting/metrics_reporting/fatal_crash/fatal_crash_events_observer_uploaded_crash_info_manager.cc",
+    "policy/reporting/metrics_reporting/fatal_crash/fatal_crash_events_observer_uploaded_crash_info_manager.h",
     "policy/reporting/metrics_reporting/metric_reporting_manager.cc",
     "policy/reporting/metrics_reporting/metric_reporting_manager.h",
     "policy/reporting/metrics_reporting/metric_reporting_prefs.cc",