Remove experiment wording from mixed autoupgrade console msg

The actual mixed-autoupgrade document still needs to be updated before
launch, this just changes the console strings in chrome to remove the
experiment wording.

Bug: 872446
Change-Id: If6c9ca4ac1926daa8627176949783313adb9d992
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1865398
Auto-Submit: Carlos IL <carlosil@chromium.org>
Commit-Queue: Mike West <mkwst@chromium.org>
Reviewed-by: Mike West <mkwst@chromium.org>
Cr-Commit-Position: refs/heads/master@{#706803}

third_party/blink/renderer/core/loader/mixed_content_checker.cc

@@ -765,7 +765,7 @@ ConsoleMessage* MixedContentChecker::CreateConsoleMessageAboutFetchAutoupgrade(
     const KURL& mixed_content_url) {
   String message = String::Format(
       "Mixed Content: The page at '%s' was loaded over HTTPS, but requested an "
-      "insecure element '%s'. As part of an experiment this request was "
+      "insecure element '%s'. This request was "
       "automatically upgraded to HTTPS, For more information see "
       "https://chromium.googlesource.com/chromium/src/+/master/docs/security/"
       "autoupgrade-mixed.md",
@@ -782,8 +782,8 @@ MixedContentChecker::CreateConsoleMessageAboutWebSocketAutoupgrade(
     const KURL& mixed_content_url) {
   String message = String::Format(
       "Mixed Content: The page at '%s' was loaded over HTTPS, but attempted "
-      "to connect to the insecure WebSocket endpoint '%s'. As part of an "
-      "experiment this request was automatically upgraded to HTTPS, For more "
+      "to connect to the insecure WebSocket endpoint '%s'. "
+      "This request was automatically upgraded to HTTPS, For more "
       "information see "
       "https://chromium.googlesource.com/chromium/src/+/master/docs/security/"
       "autoupgrade-mixed.md",

third_party/blink/web_tests/http/tests/mixed-autoupgrade/optionally/image-upgrade-console-message.https-expected.txt

-CONSOLE WARNING: line 2: Mixed Content: The page at 'https://127.0.0.1:8443/mixed-autoupgrade/optionally/image-upgrade-console-message.https.html' was loaded over HTTPS, but requested an insecure element 'http://web-platform.test:8443/mixed-autoupgrade/resources/pass.png'. As part of an experiment this request was automatically upgraded to HTTPS, For more information see https://chromium.googlesource.com/chromium/src/+/master/docs/security/autoupgrade-mixed.md
-CONSOLE WARNING: Mixed Content: The page at 'https://127.0.0.1:8443/mixed-autoupgrade/optionally/image-upgrade-console-message.https.html' was loaded over HTTPS, but requested an insecure element 'http://web-platform.test:8443/mixed-autoupgrade/resources/pass.png'. As part of an experiment this request was automatically upgraded to HTTPS, For more information see https://chromium.googlesource.com/chromium/src/+/master/docs/security/autoupgrade-mixed.md
+CONSOLE WARNING: line 2: Mixed Content: The page at 'https://127.0.0.1:8443/mixed-autoupgrade/optionally/image-upgrade-console-message.https.html' was loaded over HTTPS, but requested an insecure element 'http://web-platform.test:8443/mixed-autoupgrade/resources/pass.png'. This request was automatically upgraded to HTTPS, For more information see https://chromium.googlesource.com/chromium/src/+/master/docs/security/autoupgrade-mixed.md
+CONSOLE WARNING: Mixed Content: The page at 'https://127.0.0.1:8443/mixed-autoupgrade/optionally/image-upgrade-console-message.https.html' was loaded over HTTPS, but requested an insecure element 'http://web-platform.test:8443/mixed-autoupgrade/resources/pass.png'. This request was automatically upgraded to HTTPS, For more information see https://chromium.googlesource.com/chromium/src/+/master/docs/security/autoupgrade-mixed.md