Fix mobile user agent string not being used when PlzNavigate is enabled.

content/browser/web_contents/web_contents_impl_browsertest.cc

Index: content/browser/web_contents/web_contents_impl_browsertest.cc
diff --git a/content/browser/web_contents/web_contents_impl_browsertest.cc b/content/browser/web_contents/web_contents_impl_browsertest.cc
index 7fb10684a46add625b5bc1a10973229f86461ea7..bf807ff9339efa73103a3370a6e8e8c4abd39114 100644
--- a/content/browser/web_contents/web_contents_impl_browsertest.cc
+++ b/content/browser/web_contents/web_contents_impl_browsertest.cc
@@ -9,6 +9,7 @@
 #include "base/values.h"
 #include "build/build_config.h"
 #include "content/browser/frame_host/navigation_entry_impl.h"
+#include "content/browser/loader/resource_dispatcher_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/browser/web_contents/web_contents_impl.h"
 #include "content/browser/web_contents/web_contents_view.h"
@@ -32,6 +33,7 @@
 #include "content/public/test/test_navigation_observer.h"
 #include "content/public/test/test_utils.h"
 #include "content/shell/browser/shell.h"
+#include "content/shell/browser/shell_resource_dispatcher_host_delegate.h"
 #include "content/test/content_browser_test_utils_internal.h"
 #include "net/dns/mock_host_resolver.h"
 #include "net/test/embedded_test_server/embedded_test_server.h"
@@ -1410,4 +1412,71 @@ IN_PROC_BROWSER_TEST_F(WebContentsImplBrowserTest,
   EXPECT_TRUE(delegate.get()->request_to_lock_mouse_called_);
 }
 
+namespace {
+class TestResourceDispatcherHostDelegate
+    : public ShellResourceDispatcherHostDelegate {
+ public:
+  explicit TestResourceDispatcherHostDelegate(bool* saw_override)
+      : saw_override_(saw_override) {}
+
+  void RequestBeginning(
+      net::URLRequest* request,
+      ResourceContext* resource_context,
+      AppCacheService* appcache_service,
+      ResourceType resource_type,
+      std::vector<std::unique_ptr<ResourceThrottle>>* throttles) override {
+    CHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+    ShellResourceDispatcherHostDelegate::RequestBeginning(
+        request, resource_context, appcache_service, resource_type, throttles);
+
+    net::HttpRequestHeaders headers = request->extra_request_headers();
+    std::string user_agent;
+    CHECK(headers.GetHeader(net::HttpRequestHeaders::kUserAgent, &user_agent));
+    if (user_agent.find("foo") != std::string::npos)
+      *saw_override_ = true;
+  }
+
+ private:
+  bool* saw_override_;
+};
+}  // namespace
+
+// Checks that user agent override string is only used when it's overridden.
+IN_PROC_BROWSER_TEST_F(WebContentsImplBrowserTest, UserAgentOverride) {
+  bool saw_override = false;
+  TestResourceDispatcherHostDelegate new_delegate(&saw_override);
+  ResourceDispatcherHostDelegate* old_delegate =
+      ResourceDispatcherHostImpl::Get()->delegate();
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&ResourceDispatcherHost::SetDelegate,
+                 base::Unretained(ResourceDispatcherHostImpl::Get()),
+                 &new_delegate));
+
+  ASSERT_TRUE(embedded_test_server()->Start());
+  const GURL kUrl(embedded_test_server()->GetURL("/simple_page.html"));
+  NavigateToURL(shell(), kUrl);
+  ASSERT_FALSE(saw_override);
+
+  shell()->web_contents()->SetUserAgentOverride("foo");
+  NavigateToURL(shell(), kUrl);
+  ASSERT_FALSE(saw_override);
+
+  shell()
+      ->web_contents()
+      ->GetController()
+      .GetLastCommittedEntry()
+      ->SetIsOverridingUserAgent(true);
+  TestNavigationObserver tab_observer(shell()->web_contents(), 1);
+  shell()->web_contents()->GetController().Reload(ReloadType::NORMAL, false);
+  tab_observer.Wait();
+  ASSERT_TRUE(saw_override);
+
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&ResourceDispatcherHost::SetDelegate,
+                 base::Unretained(ResourceDispatcherHostImpl::Get()),
+                 old_delegate));
+}
+
 }  // namespace content