Reland of Add --headless flag to Windows

headless/public/util/generic_url_request_job.h

Index: headless/public/util/generic_url_request_job.h
diff --git a/headless/public/util/generic_url_request_job.h b/headless/public/util/generic_url_request_job.h
index 8830934e3f9d9b34fc31e50f7158ac327808157e..679e5ca97f6f6bc7bbfd45842297e8c81a9b7545 100644
--- a/headless/public/util/generic_url_request_job.h
+++ b/headless/public/util/generic_url_request_job.h
@@ -14,6 +14,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/single_thread_task_runner.h"
+#include "headless/public/headless_export.h"
 #include "headless/public/util/managed_dispatch_url_request_job.h"
 #include "headless/public/util/url_fetcher.h"
 #include "net/base/net_errors.h"
@@ -34,7 +35,7 @@
 class URLRequestDispatcher;
 
 // Wrapper around net::URLRequest with helpers to access select metadata.
-class Request {
+class HEADLESS_EXPORT Request {
  public:
   virtual uint64_t GetRequestId() const = 0;
 
@@ -83,7 +84,7 @@
 
 // Details of a pending request received by GenericURLRequestJob which must be
 // either Allowed, Blocked, Modified or have it's response Mocked.
-class PendingRequest {
+class HEADLESS_EXPORT PendingRequest {
  public:
   virtual const Request* GetRequest() const = 0;
 
@@ -128,7 +129,7 @@
       public PendingRequest,
       public Request {
  public:
-  class Delegate {
+  class HEADLESS_EXPORT Delegate {
    public:
     // Notifies the delegate of an PendingRequest which must either be
     // allowed, blocked, modifed or it's response mocked. Called on an arbitrary