Issue 3532 - Improved preformance of icon animation and fixed a memory leak

lib/icon.js

Index: lib/icon.js
===================================================================
--- a/lib/icon.js
+++ b/lib/icon.js
@@ -27,6 +27,7 @@
 
 let frameInterval = null;
 let animationInterval = null;
+let onActivated = null;
 let whitelistedState = new ext.PageMap();
 
 function loadImage(url)
@@ -119,30 +120,37 @@
 {
   function playAnimation(frames)
   {
-    let animationStep = 0;
     ext.pages.query({active: true}, pages =>
     {
-      function appendActivePage(page)
+      let animationStep = 0;
+      let opacity = 0;
+
+      onActivated = page =>
       {
         pages.push(page);
-      }
-      ext.pages.onActivated.addListener(appendActivePage);
+        setIcon(page, notificationType, opacity, frames);
+      };
+      ext.pages.onActivated.addListener(onActivated);
 
       frameInterval = setInterval(() =>
       {
-        let opacity = frameOpacities[animationStep++];
-        for (let page of pages)
+        let oldOpacity = opacity;
+        opacity = frameOpacities[animationStep++];
+
+        if (opacity != oldOpacity)
         {
-          if (whitelistedState.has(page))
-            setIcon(page, notificationType, opacity, frames);
-        };
+          for (let page of pages)
+          {
+            if (whitelistedState.has(page))
+              setIcon(page, notificationType, opacity, frames);
+          }
+        }
 
         if (animationStep > numberOfFrames)
         {
-          animationStep = 0;
           clearInterval(frameInterval);
-          frameInterval = null;
-          ext.pages.onActivated.removeListener(appendActivePage);
+          ext.pages.onActivated.removeListener(onActivated);
+          frameInterval = onActivated = null;
         }
       }, 100);
     });
@@ -179,7 +187,9 @@
     clearInterval(frameInterval);
   if (animationInterval != null)
     clearInterval(animationInterval);
-  frameInterval = animationInterval = null;
+  if (onActivated)
+    ext.pages.onActivated.removeListener(onActivated);
+  frameInterval = animationInterval = onActivated = null;
 };
 
 /**