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Revision 4e5f09f89e6f1976dd49a57ba46cd447c7e19a1e authored by Alex Moshchuk on 13 April 2018, 15:22:14 UTC, committed by Chromium WPT Sync on 13 April 2018, 15:22:14 UTC 
Reland: Use PostTask to schedule cross-process postMessage forwarding.
 
Changes from original attempt at https://crrev.com/c/999182:
- fix flakiness in two additional ChromeOS login tests
- fix CSP WPT tests to not depend on ordering between iframe's onload
  and postMessage - see https://crbug.com/832319.

Previously, we sent the IPC to forward a cross-process postMessage
immediately.  This caused a behavioral difference from the
same-process case where the postMessage is always scheduled.  Namely,
in a scenario like this:

  frame.postMessage(...);
  doSomethingThatSendsIPCsToFrame(frame);

the IPCs from JS following the postMessage would've been ordered
incorrectly, causing |frame| to see their side effects after the
postMessage dispatch in the cross-process case, whereas they would be
seen before the postMessage dispatch in the same-process case.  One
example of this is frame.focus(), and another is a frame element
onload event (dispatched via FrameHostMsg_DispatchLoad) arriving after
a postMessage dispatched from an inline script while the frame was
still loading.

To resolve these ordering concerns, this CL changes cross-process
postMessage to do a PostTask on the sender side before sending the
message to the browser process.  This improves the current state of
the world, but does not yet achieve a perfect match for the IPC
ordering in the same-process case - see discussion on the bug.

Bug: 828529
Change-Id: I62a627c501526d09900be4f5bd2c899acf4d1e07
Reviewed-on: https://chromium-review.googlesource.com/999182
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Alex Moshchuk <alexmos@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#550284}
Reviewed-on: https://chromium-review.googlesource.com/1011287
Cr-Commit-Position: refs/heads/master@{#550621}
1 parent f90d3d6
Raw File
first-contentful-paint.html 
<!DOCTYPE html>
<head>
<title>Performance Paint Timing Test: FP followed by FCP</title>
</head>
<body>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<div id="main"></div>
<div id="image"></div>

<script>
async_test(function (t) {
    const bufferedEntries = performance.getEntriesByType('paint');
    assert_equals(bufferedEntries.length, 0, "No paint entries yet");
    const div = document.createElement("div");
    div.style.width = "100px";
    div.style.height = "100px";
    div.style.backgroundColor = "red";
    div.style.color = "blue";
    document.getElementById("main").appendChild(div);
    function testPaintEntries() {
      const bufferedEntries = performance.getEntriesByType('paint');
      if (bufferedEntries.length < 1) {
        t.step_timeout(function() {
          testPaintEntries();
        }, 20);
        return;
      }
      t.step(function() {
        assert_equals(bufferedEntries.length, 1, "FP only.");
        assert_equals(bufferedEntries[0].entryType, "paint");
        assert_equals(bufferedEntries[0].name, "first-paint");
      });
      const img = document.createElement("IMG");
      img.src = "resources/circles.png";
      img.onload = function() {
        function secondTestPaintEntries() {
          const moreBufferedEntries = performance.getEntriesByType('paint');
          if (moreBufferedEntries.length < 2) {
            t.step_timeout(function() {
              secondTestPaintEntries();
            }, 20);
            return;
          }
          t.step(function() {
            assert_equals(moreBufferedEntries.length, 2, "FP and FCP.");
            assert_equals(moreBufferedEntries[0].entryType, "paint");
            assert_equals(moreBufferedEntries[0].name, "first-paint");
            const fpEntriesGotByName =
                performance.getEntriesByName('first-paint');
            assert_equals(fpEntriesGotByName.length, 1);
            assert_equals(moreBufferedEntries[0], fpEntriesGotByName[0]);
            assert_equals(moreBufferedEntries[1].entryType, "paint");
            assert_equals(moreBufferedEntries[1].name, "first-contentful-paint");
            const fcpEntriesGotByName =
                performance.getEntriesByName('first-contentful-paint');
            assert_equals(fcpEntriesGotByName.length, 1);
            assert_equals(moreBufferedEntries[1], fcpEntriesGotByName[0]);
            t.done();
          });
        }
        t.step(function() {
          secondTestPaintEntries();
        });
      };
      document.getElementById('image').appendChild(img);
    }
    t.step(function() {
      testPaintEntries();
    });
}, "First Paint triggered by non-contentful paint. Image load triggers First Contentful Paint.");
</script>
</body>
</html>
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