Fix SignedExchangeRequestHandlerBrowserTest on Android KitKat

Setting a mock ContentBrowserClient via SetBrowserClientForTesting
doesn't work on Android KitKat. (crbug.com/864403)

After this patch, VariantMatch and VariantMismatch test cases will be
skipped in Android version < 5.

Bug: 937930,864403
Change-Id: Ia246305fbaa906c9a3f44d45b85e6b6e69b35d1f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1501954Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Reviewed-by: Tsuyoshi Horo <horo@chromium.org>
Commit-Queue: Kunihiko Sakamoto <ksakamoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#637609}

content/browser/web_package/signed_exchange_request_handler_browsertest.cc

@@ -12,6 +12,7 @@
 #include "base/test/scoped_feature_list.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/time/time.h"
+#include "build/build_config.h"
 #include "content/browser/frame_host/navigation_handle_impl.h"
 #include "content/browser/loader/prefetch_url_loader_service.h"
 #include "content/browser/storage_partition_impl.h"
@@ -129,8 +130,18 @@ class SignedExchangeRequestHandlerBrowserTestBase
   }
 
   void SetUpOnMainThread() override {
-    original_client_ = SetBrowserClientForTesting(&client_);
     CertVerifierBrowserTest::SetUpOnMainThread();
+#if defined(OS_ANDROID)
+    // TODO(crbug.com/864403): It seems that we call unsupported Android APIs on
+    // KitKat when we set a ContentBrowserClient. Don't call such APIs and make
+    // this test available on KitKat.
+    int32_t major_version = 0, minor_version = 0, bugfix_version = 0;
+    base::SysInfo::OperatingSystemVersionNumbers(&major_version, &minor_version,
+                                                 &bugfix_version);
+    if (major_version < 5)
+      return;
+#endif
+    original_client_ = SetBrowserClientForTesting(&client_);
   }
 
   void TearDownOnMainThread() override {
@@ -162,12 +173,18 @@ class SignedExchangeRequestHandlerBrowserTestBase
     EXPECT_EQ(expected_title, title_watcher.WaitAndGetTitle());
   }
 
-  void SetAcceptLangs(const std::string langs) {
+  // Returns false if we cannot override accept languages. It happens only on
+  // Android Kitkat or older systems.
+  bool SetAcceptLangs(const std::string langs) {
+    if (!original_client_)
+      return false;
+
     client_.SetAcceptLangs(langs);
     StoragePartitionImpl* partition = static_cast<StoragePartitionImpl*>(
         BrowserContext::GetDefaultStoragePartition(
             shell()->web_contents()->GetBrowserContext()));
     partition->GetPrefetchURLLoaderService()->SetAcceptLanguages(langs);
+    return true;
   }
 
   const base::HistogramTester histogram_tester_;
@@ -263,7 +280,8 @@ IN_PROC_BROWSER_TEST_P(SignedExchangeRequestHandlerBrowserTest, Simple) {
 }
 
 IN_PROC_BROWSER_TEST_P(SignedExchangeRequestHandlerBrowserTest, VariantMatch) {
-  SetAcceptLangs("en-US,fr");
+  if (!SetAcceptLangs("en-US,fr"))
+    return;
   InstallUrlInterceptor(
       GURL("https://cert.example.org/cert.msg"),
       "content/test/data/sxg/test.example.org.public.pem.cbor");
@@ -287,7 +305,8 @@ IN_PROC_BROWSER_TEST_P(SignedExchangeRequestHandlerBrowserTest, VariantMatch) {
 
 IN_PROC_BROWSER_TEST_P(SignedExchangeRequestHandlerBrowserTest,
                        VariantMismatch) {
-  SetAcceptLangs("en-US,ja");
+  if (!SetAcceptLangs("en-US,ja"))
+    return;
   InstallUrlInterceptor(
       GURL("https://cert.example.org/cert.msg"),
       "content/test/data/sxg/test.example.org.public.pem.cbor");