Revert "Enable ClientHintsPersistent feature (Accept-CH-Lifetime header)."

This reverts commit 6af9df3e.

Reason for revert: Caused a regression as outlined in
https://chromium-review.googlesource.com/c/chromium/src/+/957265#message-bfd66cb6916d1397f05a74dd7c1fca4645857147

Original change's description:
> Enable ClientHintsPersistent feature (Accept-CH-Lifetime header).
>
> blink-dev i2s thread: https://groups.google.com/a/chromium.org/d/topic/blink-dev/8RBFue7RMXQ/discussion
>
> Change-Id: I5595b3aed72ea0cece88948f69f480f5808fce6b
> Bug: 735518,782381,816661
> TBR: raymes@chromium.org
> Reviewed-on: https://chromium-review.googlesource.com/957265
> Reviewed-by: Tarun Bansal <tbansal@chromium.org>
> Reviewed-by: David Dorwin <ddorwin@chromium.org>
> Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
> Commit-Queue: Tarun Bansal <tbansal@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#543786}

TBR=ddorwin@chromium.org,raymes@chromium.org,kinuko@chromium.org,tbansal@chromium.org

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

Bug: 735518, 782381, 816661
Change-Id: I47c42057e7d3158eeb515b993266ce0ff8e937e7
Reviewed-on: https://chromium-review.googlesource.com/968081
Commit-Queue: Raymes Khoury <raymes@chromium.org>
Reviewed-by: Raymes Khoury <raymes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543992}

chrome/browser/client_hints/client_hints_browsertest.cc

@@ -705,10 +705,6 @@ IN_PROC_BROWSER_TEST_F(ClientHintsBrowserTest,
       ->GetSettingsForOneType(CONTENT_SETTINGS_TYPE_CLIENT_HINTS, std::string(),
                               &host_settings);
   EXPECT_EQ(1u, host_settings.size());
-
-  // Clear settings.
-  HostContentSettingsMapFactory::GetForProfile(browser()->profile())
-      ->ClearSettingsForOneType(CONTENT_SETTINGS_TYPE_JAVASCRIPT);
 }
 
 // Ensure that when the JavaScript is blocked, persisted client hints are not
@@ -834,10 +830,6 @@ IN_PROC_BROWSER_TEST_F(ClientHintsBrowserTest,
   EXPECT_EQ(3u, count_client_hints_headers_seen());
   EXPECT_EQ(3u, third_party_request_count_seen());
   EXPECT_EQ(0u, third_party_client_hints_count_seen());
-
-  // Clear settings.
-  HostContentSettingsMapFactory::GetForProfile(browser()->profile())
-      ->ClearSettingsForOneType(CONTENT_SETTINGS_TYPE_JAVASCRIPT);
 }
 
 // Ensure that when the cookies is blocked, client hints are not attached to the
@@ -894,10 +886,6 @@ IN_PROC_BROWSER_TEST_F(ClientHintsBrowserTest,
   EXPECT_EQ(3u, count_client_hints_headers_seen());
   EXPECT_EQ(3u, third_party_request_count_seen());
   EXPECT_EQ(0u, third_party_client_hints_count_seen());
-
-  // Clear settings.
-  HostContentSettingsMapFactory::GetForProfile(browser()->profile())
-      ->ClearSettingsForOneType(CONTENT_SETTINGS_TYPE_COOKIES);
 }
 
 // Check the client hints for the given URL in an incognito window.

chrome/browser/content_settings/content_settings_browsertest.cc

@@ -473,19 +473,6 @@ class PepperContentSettingsSpecialCasesJavaScriptBlockedTest
     content_settings_map->SetDefaultContentSetting(
         CONTENT_SETTINGS_TYPE_JAVASCRIPT, CONTENT_SETTING_BLOCK);
   }
-
-  void SetUpCommandLine(base::CommandLine* command_line) override {
-    PepperContentSettingsSpecialCasesTest::SetUpCommandLine(command_line);
-    // ClientHintsPersistent feature queries the status of JavaScript content
-    // setting on every page load. When JavaScript is blocked, this results in
-    // tab_settings->IsContentBlocked(CONTENT_SETTINGS_TYPE_JAVASCRIPT) always
-    // returning true in RunJavaScriptBlockedTest() method. This interferes with
-    // the execution of the test.
-    // TODO: https://crbug.com/822553: Make these tests compatible with the
-    // client hints feature.
-    command_line->AppendSwitchASCII("disable-blink-features",
-                                    "ClientHintsPersistent");
-  }
 };
 
 // A sanity check to verify that the plugin that is used as a baseline below

third_party/WebKit/Source/platform/runtime_enabled_features.json5

@@ -188,7 +188,7 @@
     },
     {
       name: "ClientHintsPersistent",
-      status: "stable",
+      status: "experimental",
     },
     {
       name: "ClientPlaceholdersForServerLoFi",