Reland "Origin isolation: enable by default"

This reverts commit 0ea7d517.

Reason for revert: A fix for the problem that lead to this revert has been landed in r831153 and we need to re-enable this change to test it.

Original change's description:
> Revert "Origin isolation: enable by default"
>
> This reverts commit 824b062d.
>
> Reason for revert: Causing crashes with hosted apps in https://crbug.com/1141721.
>
> Original change's description:
> > Origin isolation: enable by default
> >
> > Intent to Ship: https://groups.google.com/a/chromium.org/g/blink-dev/c/WW4fGjvroWI
> >
> > Further work on removing origin trial code and the flags is tracked in
> > https://crbug.com/1148056 and https://crbug.com/1148057.
> >
> > Bug: 1042415
> > Change-Id: Icbeecd0b592c76d36e2111b8e4d8fe30dbb63343
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2533145
> > Commit-Queue: Domenic Denicola <domenic@chromium.org>
> > Reviewed-by: Yoav Weiss <yoavweiss@chromium.org>
> > Reviewed-by: Jochen Eisinger <jochen@chromium.org>
> > Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#826910}
>
> TBR=creis@chromium.org,alexmos@chromium.org,jochen@chromium.org,domenic@chromium.org,yoavweiss@chromium.org
>
> # Not skipping CQ checks because original CL landed > 1 day ago.
>
> Bug: 1042415, 1141721
> Change-Id: I428b190fc4c6bdf39de5ffb43226ba91851e7544
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2553209
> Reviewed-by: Domenic Denicola <domenic@chromium.org>
> Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
> Reviewed-by: Charlie Reis <creis@chromium.org>
> Commit-Queue: Charlie Reis <creis@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#829937}

TBR=creis@chromium.org,alexmos@chromium.org,domenic@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 1042415
Bug: 1141721
Change-Id: I6cf3211dc675bd2351c8dc6831e8d3e2495d8c2e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2560907Reviewed-by: James MacLean <wjmaclean@chromium.org>
Commit-Queue: James MacLean <wjmaclean@chromium.org>
Cr-Commit-Position: refs/heads/master@{#831175}

content/public/common/content_features.cc

@@ -441,7 +441,7 @@ const base::Feature kNotificationTriggers{"NotificationTriggers",
 // Note that the origin policy-based variant of origin isolation is controlled
 // by kOriginPolicy, instead.
 const base::Feature kOriginIsolationHeader{"OriginIsolationHeader",
-                                           base::FEATURE_DISABLED_BY_DEFAULT};
+                                           base::FEATURE_ENABLED_BY_DEFAULT};
 
 // Origin Policy. See https://crbug.com/751996
 const base::Feature kOriginPolicy{"OriginPolicy",

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -1381,7 +1381,7 @@
     {
       name: "OriginIsolationHeader",
       origin_trial_feature_name: "OriginIsolationHeader",
-      status: "experimental",
+      status: "stable",
     },
     {
       name: "OriginPolicy",

third_party/blink/web_tests/virtual/stable/fast/dom/Window/property-access-on-cached-window-after-frame-navigated-expected.txt

@@ -171,6 +171,7 @@ PASS oldChildWindow.onwebkittransitionend is newChildWindow.onwebkittransitionen
 PASS oldChildWindow.onwheel is newChildWindow.onwheel
 PASS oldChildWindow.opener is newChildWindow.opener
 PASS oldChildWindow.origin is newChildWindow.origin
+PASS oldChildWindow.originIsolated is newChildWindow.originIsolated
 PASS oldChildWindow.outerHeight is newChildWindow.outerHeight
 PASS oldChildWindow.outerWidth is newChildWindow.outerWidth
 PASS oldChildWindow.pageXOffset is newChildWindow.pageXOffset

third_party/blink/web_tests/virtual/stable/fast/dom/Window/property-access-on-cached-window-after-frame-removed-and-gced-expected.txt

@@ -146,6 +146,7 @@ PASS childWindow.onwebkittransitionend is null
 PASS childWindow.onwheel is null
 PASS childWindow.opener is null
 PASS childWindow.origin is 'file://'
+PASS childWindow.originIsolated is false
 PASS childWindow.outerHeight is 0
 PASS childWindow.outerWidth is 0
 PASS childWindow.pageXOffset is 0

third_party/blink/web_tests/virtual/stable/fast/dom/Window/property-access-on-cached-window-after-frame-removed-expected.txt

@@ -146,6 +146,7 @@ PASS childWindow.onwebkittransitionend is null
 PASS childWindow.onwheel is null
 PASS childWindow.opener is null
 PASS childWindow.origin is 'file://'
+PASS childWindow.originIsolated is false
 PASS childWindow.outerHeight is 0
 PASS childWindow.outerWidth is 0
 PASS childWindow.pageXOffset is 0

third_party/blink/web_tests/virtual/stable/webexposed/global-interface-listing-expected.txt

@@ -9708,6 +9708,7 @@ namespace CSS
     getter onwheel
     getter opener
     getter origin
+    getter originIsolated
     getter outerHeight
     getter outerWidth
     getter pageXOffset