Client hint feature gate (#6621)

Task/Issue URL:
https://app.asana.com/1/137249556945/project/414730916066338/task/1211100004323098?focus=true

### Description

### Steps to test this PR

_Feature 1_
- [ ]
- [ ]

### UI changes
| Before  | After |
| ------ | ----- |
!(Upload before screenshot)|(Upload after screenshot)|

Co-authored-by: Craig Russell <[email protected]>

Author: jonathanKingston

user-agent/user-agent-impl/src/main/java/com/duckduckgo/user/agent/impl/ClientBrandHintProvider.kt

@@ -50,14 +50,12 @@ class RealClientBrandHintProvider @Inject constructor(
     private var currentBranding: ClientBrandsHints = DDG
 
     override fun setDefault(settings: WebSettings) {
-        if (WebViewFeature.isFeatureSupported(WebViewFeature.USER_AGENT_METADATA)) {
-            if (clientBrandHintFeature.self().isEnabled()) {
-                logcat(VERBOSE) { "ClientBrandHintProvider: branding enabled, initialising metadata with DuckDuckGo branding" }
-                setUserAgentMetadata(settings, DEFAULT_ENABLED_BRANDING)
-            } else {
-                logcat(VERBOSE) { "ClientBrandHintProvider: branding disabled, initialising metadata with Google Chrome branding" }
-                setUserAgentMetadata(settings, DEFAULT_DISABLED_BRANDING)
-            }
+        if (clientBrandHintFeature.self().isEnabled()) {
+            logcat(VERBOSE) { "ClientBrandHintProvider: branding enabled, initialising metadata with DuckDuckGo branding" }
+            setUserAgentMetadata(settings, DEFAULT_ENABLED_BRANDING)
+        } else {
+            logcat(VERBOSE) { "ClientBrandHintProvider: branding disabled, initialising metadata with Google Chrome branding" }
+            setUserAgentMetadata(settings, DEFAULT_DISABLED_BRANDING)
         }
     }
 
@@ -136,6 +134,12 @@ class RealClientBrandHintProvider @Inject constructor(
         settings: WebSettings,
         branding: ClientBrandsHints,
     ) {
+        // Check if WebView supports user agent metadata
+        if (!WebViewFeature.isFeatureSupported(WebViewFeature.USER_AGENT_METADATA)) {
+            logcat(VERBOSE) { "ClientBrandHintProvider: USER_AGENT_METADATA not supported by WebView, skipping" }
+            return
+        }
+
         currentBranding = branding
         val metadata = WebSettingsCompat.getUserAgentMetadata(settings)
         val finalBrandList = metadata.brandVersionList.map {