Update incognito/OTR comments in profile classes.

Some minor updated regarding incognito and off the record in profile
classes.

Bug: 968028
Change-Id: I2e842f43a89f113f615d7c691a26a1326a7ccab4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1649321Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Commit-Queue: Ramin Halavati <rhalavati@chromium.org>
Cr-Commit-Position: refs/heads/master@{#667171}

chrome/browser/profiles/profile_io_data.cc

@@ -391,8 +391,8 @@ void ProfileIOData::InitializeOnUIThread(Profile* profile) {
   scoped_refptr<base::SingleThreadTaskRunner> io_task_runner =
       base::CreateSingleThreadTaskRunnerWithTraits({BrowserThread::IO});
 
-  // These members are used only for sign in, which is not enabled
-  // in incognito mode.  So no need to initialize them.
+  // These members are used only for sign in, which is not enabled in incognito
+  // and guest modes. So no need to initialize them.
   if (!IsOffTheRecord()) {
     google_services_user_account_id_.Init(prefs::kGoogleServicesUserAccountId,
                                           pref_service);

chrome/browser/profiles/profile_manager.h

@@ -348,7 +348,7 @@ class ProfileManager : public content::NotificationObserver,
   // (desktop) Guest User profile and (desktop) System Profile.
   void SetNonPersonalProfilePrefs(Profile* profile);
 
-  // For ChromeOS, determines if profile should be otr.
+  // Determines if profile should be OTR.
   bool ShouldGoOffTheRecord(Profile* profile);
 
   void RunCallbacks(const std::vector<CreateCallback>& callbacks,

chrome/browser/profiles/profiles_state.h

@@ -66,9 +66,10 @@ void UpdateProfileName(Profile* profile,
 
 #endif  // !defined(OS_CHROMEOS)
 
-// Returns whether the |browser|'s profile is a non-incognito or guest profile.
-// The distinction is needed because guest profiles are implemented as
-// incognito profiles.
+// Returns whether the |browser|'s profile is not incognito (a regular profile
+// or a guest session).
+// The distinction is needed because guest profiles and incognito profiles are
+// implemented as off-the-record profiles.
 bool IsRegularOrGuestSession(Browser* browser);
 
 // Returns true if sign in is required to browse as this profile.  Call with