PLT-3473 Made shortcuts only work for CMD on OSX (#3479)

* checked for CMD key

* changed method of checking

webapp/components/channel_header.jsx

@@ -155,7 +155,7 @@ export default class ChannelHeader extends React.Component {
     }
 
     openRecentMentions(e) {
-        if ((e.ctrlKey || e.metaKey) && e.shiftKey && e.keyCode === Constants.KeyCodes.M) {
+        if (Utils.cmdOrCtrlPressed(e) && e.shiftKey && e.keyCode === Constants.KeyCodes.M) {
             e.preventDefault();
             this.searchMentions(e);
         }

webapp/components/file_upload.jsx

@@ -280,7 +280,7 @@ class FileUpload extends React.Component {
     }
 
     keyUpload(e) {
-        if ((e.ctrlKey || e.metaKey) && e.keyCode === Constants.KeyCodes.U) {
+        if (Utils.cmdOrCtrlPressed(e) && e.keyCode === Constants.KeyCodes.U) {
             e.preventDefault();
             if (this.props.postType === 'post' && document.activeElement.id === 'post_textbox' || this.props.postType === 'comment' && document.activeElement.id === 'reply_textbox') {
                 $(this.refs.fileInput).focus().trigger('click');

webapp/components/navbar.jsx

@@ -163,7 +163,7 @@ export default class Navbar extends React.Component {
         });
     }
     showChannelSwitchModal(e) {
-        if ((e.ctrlKey || e.metaKey) && e.keyCode === Constants.KeyCodes.K) {
+        if (Utils.cmdOrCtrlPressed(e) && e.keyCode === Constants.KeyCodes.K) {
             e.preventDefault();
             this.setState({
                 showChannelSwitchModal: true

webapp/components/navbar_dropdown.jsx

@@ -70,7 +70,7 @@ export default class NavbarDropdown extends React.Component {
         document.removeEventListener('keydown', this.openAccountSettings);
     }
     openAccountSettings(e) {
-        if ((e.ctrlKey || e.metaKey) && e.shiftKey && e.keyCode === Constants.KeyCodes.A) {
+        if (Utils.cmdOrCtrlPressed(e) && e.shiftKey && e.keyCode === Constants.KeyCodes.A) {
             e.preventDefault();
             this.setState({showUserSettingsModal: true});
         }

webapp/utils/utils.jsx

@@ -32,6 +32,14 @@ export function cleanUpUrlable(input) {
     return cleaned;
 }
 
+export function isMac() {
+    return navigator.platform.toUpperCase().indexOf('MAC') >= 0;
+}
+
+export function cmdOrCtrlPressed(e) {
+    return (isMac() && e.metaKey) || (!isMac() && e.ctrlKey);
+}
+
 export function isChrome() {
     if (navigator.userAgent.indexOf('Chrome') > -1) {
         return true;