PlzNavigate: support the WebRequest API

content/public/browser/content_browser_client.h

Index: content/public/browser/content_browser_client.h
diff --git a/content/public/browser/content_browser_client.h b/content/public/browser/content_browser_client.h
index e00fd88e6e5a8eb356c858ae80d87ade941944cc..9f6c4cab1062412a1427cb85cb16d4d1ec047014 100644
--- a/content/public/browser/content_browser_client.h
+++ b/content/public/browser/content_browser_client.h
@@ -115,6 +115,7 @@ class GpuProcessHost;
 class LocationProvider;
 class MediaObserver;
 class NavigationHandle;
+class NavigationUIData;
 class PlatformNotificationService;
 class PresentationServiceDelegate;
 class QuotaPermissionContext;
@@ -753,6 +754,12 @@ class CONTENT_EXPORT ContentBrowserClient {
   virtual ScopedVector<NavigationThrottle> CreateThrottlesForNavigation(
       NavigationHandle* navigation_handle);
 
+  // PlzNavigate
+  // Called at the start of the navigation to get opaque data the embedder
+  // wants to see passed to the corresponding URLRequest on the IO thread.
+  virtual std::unique_ptr<NavigationUIData> GetNavigationUIData(
+      NavigationHandle* navigation_handle);
+
   // Allows the embedder to provide its own AudioManager implementation.
   // If this function returns nullptr, a default platform implementation
   // will be used.