1 files changed, 85 insertions, 0 deletions
diff --git a/browser/base/content/test/performance/browser_startup_flicker.js b/browser/base/content/test/performance/browser_startup_flicker.js
new file mode 100644
index 0000000000..8279a0a601
--- /dev/null
+++ b/browser/base/content/test/performance/browser_startup_flicker.js
@@ -0,0 +1,85 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/*
+ * This test ensures that there is no unexpected flicker
+ * on the first window opened during startup.
+ */
+
+add_task(async function () {
+  let startupRecorder =
+    Cc["@mozilla.org/test/startuprecorder;1"].getService().wrappedJSObject;
+  await startupRecorder.done;
+
+  // Ensure all the frame data is in the test compartment to avoid traversing
+  // a cross compartment wrapper for each pixel.
+  let frames = Cu.cloneInto(startupRecorder.data.frames, {});
+  ok(!!frames.length, "Should have captured some frames.");
+
+  let unexpectedRects = 0;
+  let alreadyFocused = false;
+  for (let i = 1; i < frames.length; ++i) {
+    let frame = frames[i],
+      previousFrame = frames[i - 1];
+    let rects = compareFrames(frame, previousFrame);
+
+    if (!alreadyFocused) {
+      // The first screenshot we get 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).
+      //
+      // On Linux we expect just one rect because we don't draw titlebar
+      // buttons in the tab bar, so we just get a whole-tab-bar color-switch.
+      const minRects = AppConstants.platform == "linux" ? 0 : 5;
+      if (rects.length > minRects && rects.every(r => r.y2 < 100)) {
+        alreadyFocused = true;
+        todo(
+          false,
+          "bug 1445161 - the window should be focused at first paint, " +
+            rects.toSource()
+        );
+        continue;
+      }
+    }
+
+    rects = rects.filter(rect => {
+      let width = frame.width;
+
+      let exceptions = [
+        /**
+         * Please don't add anything new unless justified!
+         */
+      ];
+
+      let rectText = `${rect.toSource()}, window width: ${width}`;
+      for (let e of exceptions) {
+        if (e.condition(rect)) {
+          todo(false, e.name + ", " + rectText);
+          return false;
+        }
+      }
+
+      ok(false, "unexpected changed rect: " + rectText);
+      return true;
+    });
+    if (!rects.length) {
+      info("ignoring identical frame");
+      continue;
+    }
+
+    // Before dumping a frame with unexpected differences for the first time,
+    // ensure at least one previous frame has been logged so that it's possible
+    // to see the differences when examining the log.
+    if (!unexpectedRects) {
+      dumpFrame(previousFrame);
+    }
+    unexpectedRects += rects.length;
+    dumpFrame(frame);
+  }
+  is(unexpectedRects, 0, "should have 0 unknown flickering areas");
+});