Reland of Add a NavigationThrottle to the public content/ interface

content/public/browser/navigation_throttle.h

Index: content/public/browser/navigation_throttle.h
diff --git a/content/public/browser/navigation_throttle.h b/content/public/browser/navigation_throttle.h
new file mode 100644
index 0000000000000000000000000000000000000000..ae5883b5e85828827cd63eba9fe5c87c2a72c167
--- /dev/null
+++ b/content/public/browser/navigation_throttle.h
@@ -0,0 +1,43 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_PUBLIC_BROWSER_NAVIGATION_THROTTLE_H_
+#define CONTENT_PUBLIC_BROWSER_NAVIGATION_THROTTLE_H_
+
+#include "content/common/content_export.h"
+
+namespace content {
+class NavigationHandle;
+
+// A NavigationThrottle tracks and allows interaction with a navigation on the
+// UI thread.
+class CONTENT_EXPORT NavigationThrottle {
+ public:
+  // This is returned to the NavigationHandle to allow the navigation to
+  // proceed, or to cancel it.
+  enum ThrottleCheckResult {
+    PROCEED,
+    CANCEL_AND_IGNORE,
+  };
+
+  NavigationThrottle(NavigationHandle* navigation_handle);
+  virtual ~NavigationThrottle();
+
+  // Called when a network request is about to be made for this navigation.
+  virtual ThrottleCheckResult WillStartRequest();
+
+  // Called when a server redirect is received by the navigation.
+  virtual ThrottleCheckResult WillRedirectRequest();
+
+  // The NavigationHandle that is tracking the information related to this
+  // navigation.
+  NavigationHandle* navigation_handle() const { return navigation_handle_; }
+
+ private:
+  NavigationHandle* navigation_handle_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_BROWSER_NAVIGATION_THROTTLE_H_