Only check primary profile's dev tools enablement if it's managed

If the primary profile is not manged, the kDevToolsAvailability pref
will default to 0 (allow, except for in force-installed extensions).
This matters *only* if there's a secondary profile with a more liberal
kDevToolsAvailabilityPref, because the primary profile's value would be
more retrictive then. Only evaluate the primary profile's value if it is
really managed.

      secondary profile with force-installed extensions. Set
      DeveloperToolsAvailability policy in the secondary profile's
      policy to 1 (allowed) and ensure that developer tools are usable
      in force-installed extensions.

Bug: 924973
Test: manual -- sign-in with an unmanaged primary profile and a managed
Change-Id: I1328a70664af759231ebc19bdb51a7ff1c193783
Reviewed-on: https://chromium-review.googlesource.com/c/1434316Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: Lutz Justen <ljusten@chromium.org>
Commit-Queue: Pavol Marko <pmarko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#626290}

chrome/browser/devtools/chrome_devtools_manager_delegate.cc

@@ -169,7 +169,10 @@ bool ChromeDevToolsManagerDelegate::AllowInspection(
           profile->GetPrefs());
 #if defined(OS_CHROMEOS)
   // Do not create DevTools if it's disabled for primary profile.
-  if (Profile* primary_profile = ProfileManager::GetPrimaryUserProfile()) {
+  Profile* primary_profile = ProfileManager::GetPrimaryUserProfile();
+  if (primary_profile &&
+      policy::DeveloperToolsPolicyHandler::IsDevToolsAvailabilitySetByPolicy(
+          primary_profile->GetPrefs())) {
     availability =
         policy::DeveloperToolsPolicyHandler::GetMostRestrictiveAvailability(
             availability,

chrome/browser/policy/developer_tools_policy_handler.cc

@@ -217,6 +217,12 @@ DeveloperToolsPolicyHandler::GetDevToolsAvailability(
   return static_cast<Availability>(value);
 }
 
+// static
+bool DeveloperToolsPolicyHandler::IsDevToolsAvailabilitySetByPolicy(
+    const PrefService* pref_service) {
+  return pref_service->IsManagedPreference(prefs::kDevToolsAvailability);
+}
+
 // static
 DeveloperToolsPolicyHandler::Availability
 DeveloperToolsPolicyHandler::GetMostRestrictiveAvailability(

chrome/browser/policy/developer_tools_policy_handler.h

@@ -54,6 +54,11 @@ class DeveloperToolsPolicyHandler : public ConfigurationPolicyHandler {
   // |Availability::kDisallowedForForceInstalledExtensions|.
   static Availability GetDevToolsAvailability(const PrefService* pref_service);
 
+  // Returns true if developer tools availability is set by an active policy in
+  // |pref_service|.
+  static bool IsDevToolsAvailabilitySetByPolicy(
+      const PrefService* pref_service);
+
   // Returns the most restrictive availability within [|availability_1|,
   // |availability_2|].
   static Availability GetMostRestrictiveAvailability(