Clean up Mixed Content Site Setting flag

This cleans up Mixed Content Site Setting (aka shield removal) from

launched. This still leaves the feature behind a flag in case it needs
to be used as a killswitch (that can be cleaned up after M82 branches).

chrome: //flags since the flag has already expired and the change
Change-Id: I413163573ee73953d354f6c0ed5c7be50d2644e1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2080896
Auto-Submit: Carlos IL <carlosil@chromium.org>
Reviewed-by: Emily Stark <estark@chromium.org>
Commit-Queue: Carlos IL <carlosil@chromium.org>
Cr-Commit-Position: refs/heads/master@{#746006}

chrome/browser/about_flags.cc

@@ -4745,10 +4745,6 @@ const FeatureEntry kFeatureEntries[] = {
     {"mix-browser-type-tabs", flag_descriptions::kMixBrowserTypeTabsName,
      flag_descriptions::kMixBrowserTypeTabsDescription, kOsDesktop,
      FEATURE_VALUE_TYPE(features::kMixBrowserTypeTabs)},
-
-    {"mixed-content-setting", flag_descriptions::kMixedContentSiteSettingName,
-     flag_descriptions::kMixedContentSiteSettingDescription, kOsDesktop,
-     FEATURE_VALUE_TYPE(features::kMixedContentSiteSetting)},
 #endif  // !defined(OS_ANDROID)
 
     {"enable-desktop-minimal-ui", flag_descriptions::kDesktopMinimalUIName,

chrome/browser/flag-metadata.json

@@ -2560,11 +2560,6 @@
     "owners": [ "joelhockey", "tbuckley" ],
     "expiry_milestone": 85
   },
-  {
-    "name": "mixed-content-setting",
-    "owners": [ "carlosil", "estark" ],
-    "expiry_milestone": 82
-  },
   {
     "name": "mobile-identity-consistency",
     "owners": [ "bsazonov", "droger", "msarda" ],

chrome/browser/flag_descriptions.cc

@@ -1155,12 +1155,6 @@ const char kMixBrowserTypeTabsDescription[] =
     "Allows tabs to be dragged between any browsers that support tabs, "
     "including apps";
 
-const char kMixedContentSiteSettingName[] =
-    "Blockable mixed content switch as site setting";
-const char kMixedContentSiteSettingDescription[] =
-    "Removes the blockable mixed content shield, and adds an 'Insecure "
-    "Content' site setting to allow blockable mixed content.";
-
 const char kMobileIdentityConsistencyName[] = "Mobile identity consistency";
 const char kMobileIdentityConsistencyDescription[] =
     "Enables stronger identity consistency on mobile";

chrome/browser/flag_descriptions.h

@@ -684,9 +684,6 @@ extern const char kMediaRouterCastAllowAllIPsDescription[];
 extern const char kMixBrowserTypeTabsName[];
 extern const char kMixBrowserTypeTabsDescription[];
 
-extern const char kMixedContentSiteSettingName[];
-extern const char kMixedContentSiteSettingDescription[];
-
 extern const char kMobileIdentityConsistencyName[];
 extern const char kMobileIdentityConsistencyDescription[];