Add riot-desktop shortcuts for forward/back matching browsers&slack

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

src/BasePlatform.js

@@ -188,4 +188,8 @@ export default class BasePlatform {
         const callbackUrl = this.getSSOCallbackUrl(mxClient.getHomeserverUrl(), mxClient.getIdentityServerUrl());
         window.location.href = mxClient.getSsoLoginUrl(callbackUrl.toString(), loginType); // redirect to SSO
     }
+
+    onKeyDown(ev: KeyboardEvent): boolean {
+        return false; // no shortcuts implemented
+    }
 }

src/Keyboard.ts

@@ -43,6 +43,8 @@ export const Key = {
     BACKTICK: "`",
     SPACE: " ",
     SLASH: "/",
+    SQUARE_BRACKET_LEFT: "[",
+    SQUARE_BRACKET_RIGHT: "]",
     A: "a",
     B: "b",
     C: "c",

src/components/structures/LoggedInView.js

@@ -40,6 +40,7 @@ import {Resizer, CollapseDistributor} from '../../resizer';
 import MatrixClientContext from "../../contexts/MatrixClientContext";
 import * as KeyboardShortcuts from "../../accessibility/KeyboardShortcuts";
 import HomePage from "./HomePage";
+import PlatformPeg from "../../PlatformPeg";
 // We need to fetch each pinned message individually (if we don't already have it)
 // so each pinned message may trigger a request. Limit the number per room for sanity.
 // NB. this is just for server notices rather than pinned messages in general.
@@ -407,6 +408,11 @@ const LoggedInView = createReactClass({
                     });
                     handled = true;
                 }
+                break;
+
+            default:
+                // if we do not have a handler for it, pass it to the platform which might
+                handled = PlatformPeg.get().onKeyDown(ev);
         }
 
         if (handled) {