Add support for opening the inbox via a shortcut - fixes #1134.

js/background.js

@@ -339,5 +339,10 @@
         }
     });
 
+    chrome.commands.onCommand.addListener(function(command) {
+        if (command === 'show_signal') {
+            openInbox();
+        }
+    });
 
 })();

manifest.json

@@ -30,5 +30,15 @@
       "background": {
           "page": "background.html"
       }
+    },
+
+    "commands": {
+      "show_signal": {
+        "suggested_key": {
+          "default": "Alt+S"
+        },
+        "description": "Show the Signal inbox."
+      }
     }
+
 }