Bug 1439875: Update browser_windowopen_flicker.js. r=florian

To avoid hacking around the empty window, and handle the activation issue seen
on Windows / OSX.

MozReview-Commit-ID: oK3T8FKd5n

browser/base/content/test/performance/browser_startup_flicker.js

@@ -22,16 +22,16 @@ add_task(async function() {
     let frame = frames[i], previousFrame = frames[i - 1];
     let rects = compareFrames(frame, previousFrame);
 
-    // The first screenshot we get shows an unfocused browser window for some
-    // reason. This is likely due to the test harness, so we want to ignore it.
+    // The first screenshot we get in OSX / Windows shows an unfocused browser
+    // window for some reason. See bug 1445161.
+    //
     // We'll assume the changes we are seeing are due to this focus change if
     // there are at least 5 areas that changed near the top of the screen, but
     // will only ignore this once (hence the alreadyFocused variable).
     if (!alreadyFocused && rects.length > 5 && rects.every(r => r.y2 < 100)) {
       alreadyFocused = true;
-      // This is likely an issue caused by the test harness, but log it anyway.
       todo(false,
-           "the window should be focused at first paint, " + rects.toSource());
+           "bug 1445161 - the window should be focused at first paint, " + rects.toSource());
       continue;
     }
 

browser/base/content/test/performance/browser_windowopen_flicker.js

@@ -71,17 +71,25 @@ add_task(async function() {
   win.removeEventListener("MozAfterPaint", afterPaintListener);
 
   let unexpectedRects = 0;
-  let ignoreTinyPaint = true;
+  let alreadyFocused = false;
   for (let i = 1; i < frames.length; ++i) {
     let frame = frames[i], previousFrame = frames[i - 1];
-    if (ignoreTinyPaint &&
-        previousFrame.width == 1 && previousFrame.height == 1) {
-      todo(false, "shouldn't initially paint a 1x1px window");
+    let rects = compareFrames(frame, previousFrame);
+
+    // The first screenshot we get in OSX / Windows shows an unfocused browser
+    // window for some reason. See bug 1445161.
+    //
+    // We'll assume the changes we are seeing are due to this focus change if
+    // there are at least 5 areas that changed near the top of the screen, but
+    // will only ignore this once (hence the alreadyFocused variable).
+    if (!alreadyFocused && rects.length > 5 && rects.every(r => r.y2 < 100)) {
+      alreadyFocused = true;
+      todo(false,
+           "bug 1445161 - the window should be focused at first paint, " + rects.toSource());
       continue;
     }
 
-    ignoreTinyPaint = false;
-    let rects = compareFrames(frame, previousFrame).filter(rect => {
+    rects = rects.filter(rect => {
       let inRange = (val, min, max) => min <= val && val <= max;
       let width = frame.width;