AW NS: fix q-values for accept-language

This fixes the Accept-Language request header when the Network Service
is enabled by adding back q-values for language entry (to properly
denote user preference).

No change to legacy code path.

Bug: 968287
Test: out/.../bin/system_webview_shell_apk launch 'https://httpbin.org/headers' (verify header has q-values)
Test: run_webview_instrumentation_test_apk --enable-features=NetworkService,NetworkServiceInProcess -f AcceptLanguageTest#*
Cq-Include-Trybots: luci.chromium.try:android_mojo
Change-Id: Ideb10bdf299505b40d96df8c771509a11c102ffc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1637451Reviewed-by: Changwan Ryu <changwan@chromium.org>
Commit-Queue: Nate Fischer <ntfschr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#664895}

android_webview/browser/aw_content_browser_client.cc

@@ -91,6 +91,7 @@
 #include "content/public/common/user_agent.h"
 #include "content/public/common/web_preferences.h"
 #include "net/android/network_library.h"
+#include "net/http/http_util.h"
 #include "net/log/net_log.h"
 #include "net/ssl/ssl_cert_request_info.h"
 #include "net/ssl/ssl_info.h"
@@ -338,7 +339,8 @@ AwContentBrowserClient::GetNetworkContextParams() {
   // preferred locales (http://crbug.com/898555). For now, set this to
   // "en-US,en" instead of "en-us,en", since Android guarantees region codes
   // will be uppercase.
-  context_params->accept_language = "en-US,en";
+  context_params->accept_language =
+      net::HttpUtil::GenerateAcceptLanguageHeader("en-US,en");
 
   // HTTP cache
   context_params->http_cache_enabled = true;

android_webview/browser/aw_settings.cc

@@ -261,8 +261,10 @@ void AwSettings::UpdateRendererPreferencesLocked(
     // AndroidWebview does not use per-site storage partitions.
     content::StoragePartition* storage_partition =
         content::BrowserContext::GetDefaultStoragePartition(aw_browser_context);
+    std::string expanded_language_list =
+        net::HttpUtil::ExpandLanguageList(prefs->accept_languages);
     storage_partition->GetNetworkContext()->SetAcceptLanguage(
-        net::HttpUtil::ExpandLanguageList(prefs->accept_languages));
+        net::HttpUtil::GenerateAcceptLanguageHeader(expanded_language_list));
   }
 }
 

android_webview/javatests/src/org/chromium/android_webview/test/AcceptLanguageTest.java

@@ -121,8 +121,11 @@ public class AcceptLanguageTest {
         mActivityTestRule.loadUrlSync(mAwContents, mContentsClient.getOnPageFinishedHelper(), url);
 
         // Note that we extend the base language from language-region pair.
-        String[] acceptLanguages = getAcceptLanguages(
-                mActivityTestRule.getJavaScriptResultBodyTextContent(mAwContents, mContentsClient));
+        String rawAcceptLanguages =
+                mActivityTestRule.getJavaScriptResultBodyTextContent(mAwContents, mContentsClient);
+        Assert.assertTrue("Accept-Language header should contain at least 1 q-value",
+                rawAcceptLanguages.contains(";q="));
+        String[] acceptLanguages = getAcceptLanguages(rawAcceptLanguages);
         Assert.assertArrayEquals(new String[] {"en-US", "en"}, acceptLanguages);
 
         // Our accept language list in user agent is different from navigator.languages, which is