March 2021 - Fixit week, New features, Testing, Interop, Metrics and more!

<td><td>Una’s Chrome blog post: “<a
href="https://developer.chrome.com/blog/hardware-accelerated-animations/">Updates
in hardware-accelerated animation capabilities</a>”</td></td>

<td><td><a
href="https://twitter.com/ChromiumDev/status/1366422289441566736">Tweet</a>
on Scroll-To...</td></td>

News and headlines

The above pictures show:

Bug status update

Our team did an awesome work on bug fixing this sprint...and during perf too!

This is likely due to our fixit week effort which is proudly introduced in the next chapter...

<td><td>P1s fixed: 4</td></td>

<td><td>P2s fixed: 11</td></td>

<td><td>P3s fixed: 7</td></td>

<td><td>Others (WAIs, dups): 18</td></td>

<td><td>Fixed: 2</td></td>

<td><td>Closed: 6</td></td>

<td><td>Assigned to another team: 1</td></td>

<td><td>Files containing too many subtests triggering timeouts. We cannot
always accelerate the scroll timing. The tests have a 6s budget and can take
3x longer than expected when machines are under load.</td></td>

<td><td>Incorrectly detecting the end of an animation. Waits on a gesture or
key event resolve when queued and not when handled. This can result on the
scroll end being detected before it has even started! To address, we now
wait for scroll events.</td></td>

<td><td>Landed 7 CLs</td></td>

<td><td>Removed 14 lines from test expectations.</td></td>

<td><td>Fixed 10 test files</td></td>

<td><td>Closed 8 bugs</td></td>

<td><td>Using sendkeys instead of keyDown, keyUp</td></td>

    <td><td>Landed 1 <a
    href="https://chromium-review.googlesource.com/c/chromium/src/+/2737916">CL</a>
    that fixed 4 tests.</td></td>

<td><td>Marked in TestExpectations:</td></td>

    <td><td>For <a href="https://crbug.com/893480">crbug.com/893480</a> the
    remaining 8 tests in Test Expectations need implementation keyUp/keyDown
    as it allows for multiple keys pressed at once</td></td>

    <td><td>For <a href="https://crbug.com/1140611">crbug.com/1140611</a>
    there’s “Element click intercepted error” thrown from test driver (2
    tests)</td></td>

<td><td>Few web tests flaky because pointermove coalescing was not taken
into account (1 WIP <a
href="https://chromium-review.googlesource.com/c/chromium/src/+/2745276">CL</a>,
2 tests, 5 related issues)</td></td>

<td><td>They usually have a minimal test case, easy to diagnose</td></td>

<td><td>These are crashes can happen in the real world</td></td>

<td><td>Often times it is due to our coding missing edge cases</td></td>

<td><td><a href="https://github.com/flackr/scroll-to-extension">Source</a>
code is available</td></td>

<td><td>Scrolls to selected element</td></td>

<td><td>Rejects <a
href="https://github.com/WICG/scroll-to-text-fragment/blob/main/EXTENSIONS.md#css-selector-restrictions">restricted
CSS selectors</a></td></td>

<td><td><a
href="https://chromium-review.googlesource.com/c/chromium/src/+/2716656">Calculate
minimum tick interval</a></td></td>

<td><td><a
href="https://chromium-review.googlesource.com/c/chromium/src/+/2730045">Used
in tick rate heuristic</a></td></td>

<td><td>&lt;meta name=”viewport” content=”device-width”&gt;</td></td>

<td><td>&lt;meta name=”viewport” content=”initial-scale=1”&gt; , for any
initial-scale &gt;=1 we’ll disable DTZ</td></td>

<td><td>&lt;meta name=”viewport” content=”minimum-scale=1”&gt;,
minimum-scale &gt;=1 implies initial-scale &gt;= 1</td></td>

<td><td>Combinations of the above</td></td>

Animations in display locked subtrees

kevers@ is working on this performance optimization, which effectively “pause” CSS animations/transitions that are not rendered due to content-visibility, while direct queries must still produce correct results.

The above demo shows that animation events stop firing while content is hidden, which is a direct consequence of not updating hidden animations due to the normal passage of time. Calculations requiring a fresh style update are correctly resolved on demand.

Composite background-color animation

xidachen@ fixed a crash which is due to missing repaint. He is also working on two known problems in order to restart finch experiment.

Scroll to element

flackr@ developed a scroll-to extension

Google Meet FPS optimization

zmo@ plumbed minimum tick interval of animations, which requires

After the above change, flackr@ found that meet still wasn’t showing 60fps. More investigation shows that meet had incorrect animation. Specifically 0.6s 3 keyframe animation with steps(18) should be 30fps, but 18 animation-timing-function steps is applied between each pair of keyframes. flackr@ is currently working with meet team to further optimize this.

Penetrating context menu image selection

The feature is implemented by benwgold@ where flackr@ is an active reviewer. Specifically, this feature allows right click / long press to find images below targeted element.

In this demo, an image label element completely covers the image. Without penetrating image selection, one could not save the image without inspecting the page.

Disable double tap to zoom

liviutinta@ landed CLs disabling DTZ for meta viewport tags such as:

The I2S API owners approved, and we have started finch experiment for 50% canary.

<td><td>The left one is the wrong behavior where the bottom constraint is
ignored.</td></td>

<td><td>The right one shows the correct behavior. Both bottom and top
constraints are used creating reveal and collapse effect.</td></td>

<td><td>Found ~15 google internal sites that might break by the incoming
fix</td></td>

<td><td>Started this <a
href="https://docs.google.com/document/d/1PGBW3PDWTenS8i6-k6Xsv1_MuKxqEfX8o1jVGmxxnFk/edit#">doc</a>,
which provided guidance on how to change their sites to avoid
breakage.</td></td>

<td><td>All google internal sites listed in the doc have made
changes.</td></td>

<td><td>Unfortunately the percentage of sites that might break is not going
down (<a
href="https://uma.googleplex.com/p/chrome/timeline_v2/?sid=29901cc34c7b4b624f5a759bda0b5a34">Beta</a>:
~2.2%, <a
href="https://uma.googleplex.com/p/chrome/timeline_v2/?sid=706cc2310b84fa2bdb3e87b52b1c052b">Stable</a>:
~0.5% of page loads)</td></td>

Sticky interop investigation

flackr@ created meta tracking bug for this. During this sprint, 3 issues were closed. Moreover, a WPT test has been landed to track new spec scrollIntoView behavior.

Fixed falsely overconstrained stick positioning

flackr@ fixed a stick position bug. In the above demo:

Overscroll-behavior propagation

xidachen@ made some progress towards fixing this bug, which includes

Scroll snap behavior with scrollbar arrow keys

Resolved the scroll snap behavior for interactions with the scrollbar arrow keys during the last sprint cycle for main thread scrolling. Fixed for composited scrolling this sprint.

<td><td><a
href="https://github.com/w3c/pointerevents/pull/349">Reword/expand
touch-action definition</a></td></td>

    <td><td>Added direct suggestions to clarify that “touch-action:
    manipulation” excludes double-tap zoom.</td></td>

<td><td><a href="https://github.com/w3c/pointerevents/pull/350">Major
refactoring: refer to “direct manipulation” rather than
“touch”</a></td></td>

    <td><td>A long and tricky edit to officially include (some) pen pointers
    in touch-action.</td></td>