In nearly every version of Chrome we see a significant number of updates and improvements to the product, its performance, and also capabilities of the web platform.
In Chrome 50 (Estimated beta date: March 10 to 17) there are a number of changes to Chrome. This list is subject to change at any time.
AppCache deprecated on insecure contexts
TL;DR: To hinder cross-site scripting, we're deprecating AppCache on insecure origins. We expect that in Chrome 52 it will only work on origins serving content over HTTPS.
Intent to Remove | Chromestatus Tracker | Chromium Bug
AppCache is a feature that allows offline and persistent access to an origin, which is a powerful privilege escalation for an cross-site scripting attack. As part of a larger effort to remove powerful features on insecure origins.
Chrome is removing this attack vector by only allowing it over HTTPS. We're deprecating HTTP support in Chrome 50 and expect to remove it entirely in Chrome 52.
Document.defaultCharset is removed
TL;DR: document.defaultCharset has
been removed to improve spec compliance.
Intent to Remove | Chromestatus Tracker | CRBug Issue
The document.defaultCharset, deprecated in Chrome 49, is a read-only property
that returns the default character encoding of the user's system based on their
regional settings. It's not been found to be useful to maintain this value
because of the way that browsers use the character encoding information in the
HTTP Response or in the meta tag embedded in the page.
Instead, use document.characterSet to get the first value specified in the
HTTP header. If that is not present then you will get the value specified in the
charset attribute of the <meta> element (for example, <meta
charset="utf-8">). Finally if none of those are available the
document.characterSet will be the user's system setting.
You can read more discussion of the reasoning not to spec this out in this github issue
Subresource attribute removed from link element
TL;DR: Remove support for the subresource value for the rel attribute of
HTMLLinkElement.
Intent to Remove | Chromestatus Tracker | Chromium Bug
The intent of the subresource attribute on <link> was to prefetch a
resource during a browser's idle time. After a browser downloaded a page, it
could then pre-download resources such as other pages so that when they were
requested by users, they could simply be retrieved from the browser cache.
The subresource attribute suffered from a number of problems. First, it never
worked as intended. Referenced resources were downloaded with low priority. The
attribute was never implemented on any browser other than Chrome. The Chrome
implementation had a bug that caused resources to be downloaded twice.
Developers looking to improve the user experience through preloading of content
have a number of options, the most customizable of which is to build a service
worker to take advantage of precaching and the Caches API. Additional solutions
include other values for the rel attribute
including preconnect, prefetch, preload, prerender. Some of these
options are experimental and may not be widely supported.
Remove insecure TLS version fallback
TL;DR: Remove a mechanism for forcing servers to return data using less- or non-secure versions of TLS.
Intent to Remove | Chromestatus Tracker | Chromium Bug
Transport layer security (TLS) supports a mechanism for negotiating versions, allowing for the introduction of new TLS versions without breaking compatibility. Some servers implemented this in such a way that browsers were required to use insecure endpoints as a fallback. Because of this, attackers could force any website, not just those that are incorrectly configured, to negotiate for weaker versions of TLS.
Affected sites will fail to connect with ERR_SSL_FALLBACK_BEYOND_MINIMUM_VERSION. Administrators
should ensure their server software is up-to-date. If still unresolved, contact the server
software vendor to see if a fix is available.
Remove KeyboardEvent.prototype.keyLocation
TL;DR: Remove an unneeded alias for the Keyboard.prototype.location
attribute.
Intent to Remove | Chromestatus Tracker | Chromium Bug
This attribute is simply an alias to the Keyboard.prototype.location
attribute, which allows disambiguation between keys that are located multiple
places on a keyboard. For example, both attributes allow developers to
distinguish between the two Enter keys on an extended keyboard.
Error and success handlers required in RTCPeerConnection methods
TL;DR: The WebRTC
RTCPeerConnection methods createOffer()
and createAnswer()
now require an error handler as well as a success handler. Previously it had
been possible to call these methods with only a success handler. That usage is
deprecated.
Intent to Remove | Chromestatus Tracker | Chromium Bug
In Chrome 49we added a warning if you call
setLocalDescription()
or setRemoteDescription()
without supplying an error handler. The error handler argument is mandatory as of Chrome 50.
This is part of clearing the way for introducing promises on these methods, as required by the WebRTC spec.
Here's an example from the WebRTC RTCPeerConnection demo (main.js, line 126):
function onCreateOfferSuccess(desc) {
pc1.setLocalDescription(desc, function() {
onSetLocalSuccess(pc1);
}, onSetSessionDescriptionError);
pc2.setRemoteDescription(desc, function() {
onSetRemoteSuccess(pc2);
}, onSetSessionDescriptionError);
pc2.createAnswer(onCreateAnswerSuccess, onCreateSessionDescriptionError);
}
Note that both setLocalDescription() and setRemoteDescription() have an
error handler. Older browsers expecting only a success handler will simply
ignore the error handler argument if it's present; calling this code in an older
browser will not cause an exception.
In general, for production WebRTC applications we recommend that you use
adapter.js, a shim, maintained by the
WebRTC project, to insulate apps from spec changes and prefix differences.
The XMLHttpRequestProgressEvent is no longer supported
TL;DR: The XMLHttpRequestProgressEvent interface will be removed, together
with the attributes position and totalSize.
Intent to Remove | Chromestatus Tracker | Chromium Bug
This event existed to support the Gecko compatibility properties position and
totalSize. Support for all three was dropped in Mozilla 22 and the
functionality has long been superseded by the
ProgressEvent.
var progressBar = document.getElementById("p"),
client = new XMLHttpRequest()
client.open("GET", "magical-unicorns")
client.onprogress = function(pe) {
if(pe.lengthComputable) {
progressBar.max = pe.total
progressBar.value = pe.loaded
}
}
Remove prefixed Encrypted Media Extensions
TL;DR: Prefixed encrypted media extensions have been removed in favor of a spec-based, unprefixed replacement.
Intent to Remove | Chromestatus Tracker | Chromium Bug
In Chrome 42, we shipped a specification-based,
unprefixed version of encrypted media extensions. This API is used to discover,
select, and interact with Digital Rights Management systems for use with
HTMLMediaElement.
That was nearly a year ago. And since the unprefixed version has more capabilities than the prefixed version, it's time to remove the prefixed version of the API.
Remove support for SVGElement.offset properties
TL;DR: Offset properties for SVGElement have been dropped in favor of the more
widely-supported properties on HTMLElement.
Intent to Remove | Chromestatus Tracker | Chromium Bug
Offset properties have long been supported by both HTMLElement and
SVGElement; however, Gecko and Edge only support them on HTMLElement. To
improve consistency between browsers these properties were deprecated in Chrome
48 and are now being removed.
Though equivalent properties are part of HTMLElement, developers looking for
an alternative can also use
getBoundingClientRect()