Update IncognitoModePrefs::CanOpenBrowser to use IsIncognitoProfile.

CanOpenBrowser used IsOffTheRecordProfile instead of IsIncognitoProfile,
applying incognito policy selections on all OTR profiles.

It's now updated to only affect incognito.

Bug: 1033903, 968028
Change-Id: I889cbbcacfe2fb0a42c81debc6d738487e1fdd5b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2249932Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Reviewed-by: Dominic Battré <battre@chromium.org>
Commit-Queue: Ramin Halavati <rhalavati@chromium.org>
Cr-Commit-Position: refs/heads/master@{#781250}

chrome/browser/prefs/incognito_mode_prefs.cc

@@ -77,18 +77,15 @@ bool IncognitoModePrefs::ShouldLaunchIncognito(
 
 // static
 bool IncognitoModePrefs::CanOpenBrowser(Profile* profile) {
-  if (profile->IsGuestSession())
-    return true;
-
   switch (GetAvailability(profile->GetPrefs())) {
     case IncognitoModePrefs::ENABLED:
       return true;
 
     case IncognitoModePrefs::DISABLED:
-      return !profile->IsOffTheRecord();
+      return !profile->IsIncognitoProfile();
 
     case IncognitoModePrefs::FORCED:
-      return profile->IsOffTheRecord();
+      return profile->IsIncognitoProfile();
 
     default:
       NOTREACHED();