Enable NavigationRequestPreconnect on WebView.

This was an oversight when the feature was added. I'll use Finch to measure the effect.

(cherry picked from commit 8948da2)

Bug: 1276493
Change-Id: Ia75ef74b9fd832dd0043284c72b9ab9b558e6d0b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4189306
Reviewed-by: Richard Coles <torne@chromium.org>
Commit-Queue: Richard Coles <torne@chromium.org>
Auto-Submit: John Abd-El-Malek <jam@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1096336}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4195634
Cr-Commit-Position: refs/branch-heads/5481@{#692}
Cr-Branched-From: 130f3e4-refs/heads/main@{#1084008}

android_webview/browser/aw_content_browser_client.cc

@@ -1043,6 +1043,11 @@ bool AwContentBrowserClient::SuppressDifferentOriginSubframeJSDialogs(
       features::kWebViewSuppressDifferentOriginSubframeJSDialogs);
 }
 
+bool AwContentBrowserClient::ShouldPreconnectNavigation(
+    content::BrowserContext* browser_context) {
+  return true;
+}
+
 void AwContentBrowserClient::OnDisplayInsecureContent(
     content::WebContents* web_contents) {
   AwSettings* aw_settings = AwSettings::FromWebContents(web_contents);

android_webview/browser/aw_content_browser_client.h

@@ -241,6 +241,8 @@ class AwContentBrowserClient : public content::ContentBrowserClient {
   bool HasErrorPage(int http_status_code) override;
   bool SuppressDifferentOriginSubframeJSDialogs(
       content::BrowserContext* browser_context) override;
+  bool ShouldPreconnectNavigation(
+      content::BrowserContext* browser_context) override;
   void OnDisplayInsecureContent(content::WebContents* web_contents) override;
 
   AwFeatureListCreator* aw_feature_list_creator() {

android_webview/java/src/org/chromium/android_webview/common/ProductionSupportedFlagList.java

@@ -361,6 +361,7 @@ private ProductionSupportedFlagList() {}
             Flag.baseFeature(ContentSwitches.DISABLE_DOMAIN_BLOCKING_FOR3DAP_IS,
                     "Disable the per-domain blocking for 3D APIs after GPU reset. "
                             + "This switch is intended only for tests."),
+            Flag.baseFeature("NavigationRequestPreconnect"),
             // Add new commandline switches and features above. The final entry should have a
             // trailing comma for cleaner diffs.
     };