Revert "Add domain joined check to managed device detection for DoH."

This reverts commit a50dfe61.

Reason for revert: Possible cause of crbug.com/998385.

Original change's description:
> Add domain joined check to managed device detection for DoH.
>
> Some devices may be domain joined but not have any active policies.
> We should also disable DoH by default for that scenario.
>
> Bug: 955454
> Change-Id: I50ad015e9e5d072dddcaa72524e5d39ffb2e005c
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1773397
> Reviewed-by: Eric Orth <ericorth@chromium.org>
> Commit-Queue: Katharine Daly <dalyk@google.com>
> Cr-Commit-Position: refs/heads/master@{#690809}

TBR=ericorth@chromium.org,dalyk@google.com

Change-Id: I22da3426da2a759230917f18b3d81d4075ecd9d5
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 955454
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1772934Reviewed-by: Darren Shen <shend@chromium.org>
Commit-Queue: Darren Shen <shend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#691044}

chrome/browser/net/dns_util.cc

@@ -10,10 +10,6 @@
 #include "net/third_party/uri_template/uri_template.h"
 #include "url/gurl.h"
 
-#if defined(OS_WIN)
-#include "base/enterprise_util.h"
-#endif
-
 namespace chrome_browser_net {
 
 bool IsValidDohTemplate(const std::string& server_template,
@@ -47,12 +43,8 @@ bool IsValidDohTemplate(const std::string& server_template,
 
 bool ShouldDisableDohForManaged() {
 #if !defined(OS_ANDROID) && !defined(OS_CHROMEOS)
-  if (g_browser_process->browser_policy_connector()->HasMachineLevelPolicies())
-    return true;
-#endif
-#if defined(OS_WIN)
-  if (base::IsMachineExternallyManaged())
-    return true;
+  return g_browser_process->browser_policy_connector()
+      ->HasMachineLevelPolicies();
 #endif
   return false;
 }

chrome/browser/net/dns_util.h

@@ -16,11 +16,11 @@ namespace chrome_browser_net {
 bool IsValidDohTemplate(const std::string& server_template,
                         std::string* server_method);
 
-// Returns true if there are any active machine level policies or if the machine
-// is domain joined. This special logic is used to disable DoH by default for
-// Desktop platforms (the enterprise policy field default_for_enterprise_users
-// only applies to ChromeOS). We don't attempt enterprise detection on Android
-// at this time.
+// Returns true if any machine level policies. ChromeOS devices are already
+// handled by the default_for_enterprise_users field on the DoH policy. We don't
+// attempt enterprise detection on Android at this time. This special logic is
+// to prevent enterprises from having DoH enabled by default and is necessary
+// because default_for_enterprise_users only applies to ChromeOS.
 bool ShouldDisableDohForManaged();
 
 const char kDnsOverHttpsModeOff[] = "off";