Add metric for Guest profile startup trigger.

Adds "Profile.Guest.ForcedByPolicy" metric which records if Guest
profiles are initiated by user request or forced by policy.

Bug: 1125474, 1167473
Change-Id: I8c87096bd60d260c1542a1c869361f3f5ed2cb43
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2632586
Auto-Submit: Ramin Halavati <rhalavati@chromium.org>
Reviewed-by: Jesse Doherty <jwd@chromium.org>
Reviewed-by: David Roger <droger@chromium.org>
Commit-Queue: Jesse Doherty <jwd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#844896}

chrome/browser/profiles/profile_impl.cc

@@ -25,6 +25,7 @@
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/weak_ptr.h"
+#include "base/metrics/histogram_functions.h"
 #include "base/no_destructor.h"
 #include "base/path_service.h"
 #include "base/sequenced_task_runner.h"
@@ -565,6 +566,16 @@ ProfileImpl::ProfileImpl(
     // Prefs were loaded synchronously so we can continue directly.
     OnPrefsLoaded(create_mode, true);
   }
+
+#if !defined(OS_ANDROID)
+  if (IsGuestSession() || IsEphemeralGuestProfile()) {
+    PrefService* local_state = g_browser_process->local_state();
+    DCHECK(local_state);
+    base::UmaHistogramBoolean(
+        "Profile.Guest.ForcedByPolicy",
+        local_state->GetBoolean(prefs::kBrowserGuestModeEnforced));
+  }
+#endif  // !defined(OS_ANDROID)
 }
 
 #if defined(OS_ANDROID)

tools/metrics/histograms/histograms_xml/profile/histograms.xml

@@ -207,6 +207,16 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   <summary>Size of the favicons database.</summary>
 </histogram>
 
+<histogram name="Profile.Guest.ForcedByPolicy" enum="BooleanForced"
+    expires_after="M92">
+  <owner>rhalavati@chromium.org</owner>
+  <owner>chrome-privacy-core@google.com</owner>
+  <summary>
+    Records if a Guest session is started by user's request or is forced by a
+    policy. This is recorded when a Guest profile is created.
+  </summary>
+</histogram>
+
 <histogram name="Profile.Guest.{Type}.Lifetime" units="minutes"
     expires_after="2021-06-01">
   <owner>rhalavati@chromium.org</owner>