Enable The Sec-CH-UA-Form-Factors hint by default

When this feature is enabled, the hint is not sent by default, as it is
a high-entropy hint. So, enabling this feature has no impact unless a
site requests the hint.

I2S: https://groups.google.com/a/chromium.org/g/blink-dev/c/CVOCZ26iqMY/m/osIPJrQ_AAAJ

Bug: 40910451
Change-Id: Ifa4299ef6bd96e23e008aff633bdf075ee25791f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5374782
Reviewed-by: Robert Flack <flackr@chromium.org>
Reviewed-by: Bo Liu <boliu@chromium.org>
Commit-Queue: Dustin Mitchell <djmitche@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1274122}
diff --git a/android_webview/javatests/src/org/chromium/android_webview/test/ClientHintsTest.java b/android_webview/javatests/src/org/chromium/android_webview/test/ClientHintsTest.java
index 0cecc0f..6e296e8 100644
--- a/android_webview/javatests/src/org/chromium/android_webview/test/ClientHintsTest.java
+++ b/android_webview/javatests/src/org/chromium/android_webview/test/ClientHintsTest.java
@@ -246,7 +246,7 @@
         Assert.assertEquals("HEADER_NOT_FOUND", clientHintsMap.get("save-data"));
         Assert.assertNotEquals(
                 "HEADER_NOT_FOUND", clientHintsMap.get("sec-ch-prefers-reduced-motion"));
-        Assert.assertEquals("HEADER_NOT_FOUND", clientHintsMap.get("sec-ch-ua-form-factors"));
+        Assert.assertNotEquals("HEADER_NOT_FOUND", clientHintsMap.get("sec-ch-ua-form-factors"));
         Assert.assertNotEquals(
                 "HEADER_NOT_FOUND", clientHintsMap.get("sec-ch-prefers-reduced-transparency"));
 
diff --git a/third_party/blink/common/features.cc b/third_party/blink/common/features.cc
index 28c6dd76..c123564 100644
--- a/third_party/blink/common/features.cc
+++ b/third_party/blink/common/features.cc
@@ -583,7 +583,7 @@
 // Enable `form-factors` client hint.
 BASE_FEATURE(kClientHintsFormFactors,
              "ClientHintsFormFactors",
-             base::FEATURE_DISABLED_BY_DEFAULT);
+             base::FEATURE_ENABLED_BY_DEFAULT);
 
 // Enable `sec-ch-prefers-reduced-transparency` client hint.
 BASE_FEATURE(kClientHintsPrefersReducedTransparency,