Index: lib/adblockplus.js
===================================================================
--- a/lib/adblockplus.js
+++ b/lib/adblockplus.js
@@ -357,45 +357,58 @@
     return keyPrefix + (file instanceof FakeFile ? file.path : file.spec);
   }
 
-  function loadFile(file, successCallback, errorCallback)
-  {
-    var key = fileToKey(file);
-    var entry = localStorage.getItem(key);
-    if (entry)
-    {
-      successCallback(JSON.parse(entry));
-    }
-    else
-    {
-      // Also check the chrome.storage.local
-      // We may have a init data there
+  function loadFile(file)
+  {
+    return new Promise(function(resolve, reject)
+    {
+      var key = fileToKey(file);
       ext.storage.get([key], function(items)
       {
         var entry = items[key];
+        if (!entry)
+        {
+          try
+          {
+            entry = JSON.parse(window.localStorage.getItem(key));
+          }
+          catch (err)
+          {}
+        }
         if (entry)
-          successCallback(entry);
+        {
+          resolve(entry);
+        }
         else
-          errorCallback(new Error("File doesn't exist"));
+        {
+          reject(new Error("File doesn't exist"));
+        }
       });
-    }
+    }.bind(this));
   }
   function saveFile(file, data, callback)
   {
-    try
-    {
-      localStorage.setItem(fileToKey(file), JSON.stringify({
-        content: data,
-        lastModified: Date.now()
-      }));
-    }
-    catch(error)
-    {
-      // QuotaExceededError can happen. Notify the user and ignore
-      var errorMessage = "Subscription storage is full. " + 
-        "Please remove some subscriptions and try again.";
-      alert(errorMessage);
-      callback(new Error(errorMessage));
-      return;
+    var entry = {};
+    var key = fileToKey(file);
+
+    if (typeof browser == "undefined")
+    {
+      entry[key] = {
+        lastModified: Date.now(),
+        content: data
+      };
+      ext.storage.set(entry, callback);
+    }
+    else
+    {
+      var processedData = LZString.compressToUTF16(JSON.stringify(data));
+      ext.storage.remove(key);
+      entry[key] = {
+        lastModified: Date.now(),
+        content: processedData,
+        compressed: true
+      };
+      window.localStorage.setItem(key, JSON.stringify(entry[key]));
+      setTimeout(callback, 0);
     }
     callback();
   }
@@ -408,15 +421,21 @@
     {
       function onLoaded(entry)
       {
-        for (var _loopIndex1 = 0; _loopIndex1 < entry.content.length; ++_loopIndex1)
-        {
-          var line = entry.content[_loopIndex1];
-          listener.process(line);
-        }
-        listener.process(null);
+        if ("content" in entry)
+        {
+          if (entry["compressed"])
+          {
+            entry.content = JSON.parse(LZString.decompressFromUTF16(entry.content));
+          }
+          for (var _loopIndex15 = 0; _loopIndex15 < entry.content.length; ++_loopIndex15)
+          {
+            var line = entry.content[_loopIndex15];
+            listener.process(line);
+          }
+        }
         callback(null);
       }
-      loadFile(file, onLoaded, callback);
+      loadFile(file).then(onLoaded, callback);
     },
     writeToFile: function(file, data, callback)
     {
@@ -428,7 +447,7 @@
       {
         saveFile(toFile, entry.content, callback);
       }
-      loadFile(fromFile, onLoaded, callback);
+      loadFile(file).then(onLoaded, callback);
     },
     renameFile: function(fromFile, newName, callback)
     {
@@ -439,7 +458,7 @@
           ext.storage.set(keyPrefix + newName, entry, callback);
         });
       }
-      loadFile(fromFile, onLoaded, callback);
+      loadFile(file).then(onLoaded, callback);
     },
     removeFile: function(file, callback)
     {
@@ -455,7 +474,7 @@
           lastModified: entry.lastModified
         });
       }
-      loadFile(file, onLoaded, callback);
+      loadFile(file).then(onLoaded, callback);
     }
   };
   return exports;