Fixed various issues in older Chrome versions

chrome/common.js

Index: chrome/common.js
===================================================================
--- a/chrome/common.js
+++ b/chrome/common.js
@@ -51,33 +51,55 @@
         this._listeners.splice(idx, 1);
         this._wrappedListeners.splice(idx, 1);
       }
     }
   };
 
   var MessageEventTarget = function()
   {
-    WrappedEventTarget.call(this, (chrome.runtime || {}).onMessage || chrome.extension.onRequest);
+    var target;
+    if ("runtime" in chrome && "onMessage" in chrome.runtime)
+      target = chrome.runtime.onMessage;
+    else if ("onMessage" in chrome.extension)
+      target = chrome.extension.onMessage;
+    else
+      target = chrome.extension.onRequest;
+    WrappedEventTarget.call(this, target);
   };
   MessageEventTarget.prototype = {
     __proto__: WrappedEventTarget.prototype,
     _wrapListener: function(listener) {
       return function(message, sender, sendResponse)
       {
-        return listener(message, {tab: sender.tab && new Tab(sender.tab)}, sendResponse);
+        if (sender.tab && sender.tab.id >= 0)
+          sender.tab = new Tab(sender.tab);
+        return listener(message, sender, sendResponse);
       };
     }
   };
 
 
   /* API */
 
   ext = {
-    backgroundPage: {
-      sendMessage: (chrome.runtime || {}).sendMessage || chrome.extension.sendRequest,
-      getWindow: chrome.extension.getBackgroundPage
-    },
+    backgroundPage: {},
     getURL: chrome.extension.getURL,
     onMessage: new MessageEventTarget(),
     i18n: chrome.i18n
   };
+
+  if ("runtime" in chrome && "sendMessage" in chrome.runtime)
+    ext.backgroundPage.sendMessage = chrome.runtime.sendMessage;
+  else if ("sendMessage" in chrome.extension)
+    ext.backgroundPage.sendMessage = chrome.extension.sendMessage;
+  else
+    ext.backgroundPage.sendMessage = chrome.extension.sendRequest;
+
+  try

[Sebastian Noack, 2013/12/19 10:38:59]

I would prefer to wrap chrome.extension.getBackgroundPage() in a function
instead of catching the exception here. So the caller gets the original
exception.

  ext = {
    backgroundPage:
    {
      getWindow: function()
      {
        return chrome.extension.getBackgroundPage();
      }
    },
    ...
  }

[Wladimir Palant, 2013/12/19 10:47:17]

True, that's a better solution - done.

+  {
+    ext.backgroundPage.getWindow = chrome.extension.getBackgroundPage;
+  }
+  catch (e)
+  {
+    // This exception is expected in content scripts in older Chrome versions.
+  }
 })();