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

blink-dev i2s thread: https://groups.google.com/a/chromium.org/d/topic/blink-dev/8RBFue7RMXQ/discussion

Bug: 735518,782381,816661
Change-Id: Ic7c8a6a0eaf323d3ab736ac8e3ad2d23104ae0cb
Reviewed-on: https://chromium-review.googlesource.com/969407Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Tarun Bansal <tbansal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544285}

chrome/browser/client_hints/client_hints_browsertest.cc

@@ -721,6 +721,10 @@ 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
@@ -848,6 +852,10 @@ 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
@@ -905,6 +913,10 @@ 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.

third_party/WebKit/Source/platform/runtime_enabled_features.json5

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