Disable ACTION_BOOT_COMPLETED event for 3rd party apps.

chrome/browser/about_flags.cc

Index: chrome/browser/about_flags.cc
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 4c7315bcd75151acdd16cd3c955bcf0f98162ba3..cf8fe62143d09cc1b2f3d7135cc237998e75afdf 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -2102,6 +2102,13 @@ const FeatureEntry kFeatureEntries[] = {
     {"material-security-verbose", IDS_FLAGS_MATERIAL_SECURITY_VERBOSE_NAME,
      IDS_FLAGS_MATERIAL_SECURITY_VERBOSE_DESCRIPTION, kOsDesktop,
      MULTI_VALUE_TYPE(kSecurityVerboseChoices)},
+#if defined(OS_CHROMEOS)
+    {"disable-arc-boot-completed-broadcast",
+     IDS_FLAGS_ARC_ACTION_BOOT_COMPLETED,
+     IDS_FLAGS_ARC_ACTION_BOOT_COMPLETED_DESCRIPTION, kOsCrOS,
+     SINGLE_VALUE_TYPE(chromeos::switches::kDisableArcBootCompletedBroadcast)
+    },
+#endif
     // NOTE: Adding new command-line switches requires adding corresponding
     // entries to enum "LoginCustomFlags" in histograms.xml. See note in
     // histograms.xml and don't forget to run AboutFlagsHistogramTest unit test.