Revert "Only show DevTools warning about unrecognized build in Chrome (facebook#22571)"

This reverts commit b72dc8e.

Author: Juan Tejada

packages/react-devtools-extensions/src/checkForDuplicateInstallations.js

@@ -10,16 +10,13 @@
 declare var chrome: any;
 
 import {__DEBUG__} from 'react-devtools-shared/src/constants';
-import {getBrowserName} from './utils';
 import {
   EXTENSION_INSTALL_CHECK,
   EXTENSION_INSTALLATION_TYPE,
   INTERNAL_EXTENSION_ID,
   LOCAL_EXTENSION_ID,
 } from './constants';
 
-const IS_CHROME = getBrowserName() === 'Chrome';
-
 const UNRECOGNIZED_EXTENSION_ERROR =
   'React Developer Tools: You are running an unrecognized installation of the React Developer Tools extension, which might conflict with other versions of the extension installed in your browser. ' +
   'Please make sure you only have a single version of the extension installed or enabled. ' +
@@ -79,17 +76,14 @@ export function checkForDuplicateInstallations(callback: boolean => void) {
       break;
     }
     case 'unknown': {
-      // TODO: Support duplicate extension detection in other browsers
-      if (IS_CHROME) {
-        // If we don't know how this extension was built, we can't reliably detect if there
-        // are other installations of DevTools present.
-        // In this case, assume there are no duplicate exensions and show a warning about
-        // potential conflicts.
-        console.error(UNRECOGNIZED_EXTENSION_ERROR);
-        chrome.devtools.inspectedWindow.eval(
-          `console.error("${UNRECOGNIZED_EXTENSION_ERROR}")`,
-        );
-      }
+      // If we don't know how this extension was built, we can't reliably detect if there
+      // are other installations of DevTools present.
+      // In this case, assume there are no duplicate exensions and show a warning about
+      // potential conflicts.
+      console.error(UNRECOGNIZED_EXTENSION_ERROR);
+      chrome.devtools.inspectedWindow.eval(
+        `console.error("${UNRECOGNIZED_EXTENSION_ERROR}")`,
+      );
       callback(false);
       break;
     }