Fix missing HEADLESS_EXPORT defines

headless/public/util/testing/generic_url_request_mocks.h

Index: headless/public/util/testing/generic_url_request_mocks.h
diff --git a/headless/public/util/testing/generic_url_request_mocks.h b/headless/public/util/testing/generic_url_request_mocks.h
index 8483e569139dac00dc064587aa8d297dca03951c..177c3b1b49f7bf4d7ffec9981b11c330c0e4ac15 100644
--- a/headless/public/util/testing/generic_url_request_mocks.h
+++ b/headless/public/util/testing/generic_url_request_mocks.h
@@ -9,6 +9,7 @@
 #include <string>
 
 #include "base/macros.h"
+#include "headless/public/headless_export.h"
 #include "headless/public/util/generic_url_request_job.h"
 #include "headless/public/util/testing/generic_url_request_mocks.h"
 #include "net/cookies/cookie_store.h"
@@ -18,7 +19,8 @@
 
 namespace headless {
 
-class MockGenericURLRequestJobDelegate : public GenericURLRequestJob::Delegate {
+class HEADLESS_EXPORT MockGenericURLRequestJobDelegate
+    : public GenericURLRequestJob::Delegate {
  public:
   MockGenericURLRequestJobDelegate();
   ~MockGenericURLRequestJobDelegate() override;
@@ -50,7 +52,7 @@ class MockGenericURLRequestJobDelegate : public GenericURLRequestJob::Delegate {
 };
 
 // TODO(alexclarke): We may be able to replace this with the CookieMonster.
-class MockCookieStore : public net::CookieStore {
+class HEADLESS_EXPORT MockCookieStore : public net::CookieStore {
  public:
   MockCookieStore();
   ~MockCookieStore() override;
@@ -128,7 +130,8 @@ class MockCookieStore : public net::CookieStore {
   DISALLOW_COPY_AND_ASSIGN(MockCookieStore);
 };
 
-class MockURLRequestDelegate : public net::URLRequest::Delegate {
+class HEADLESS_EXPORT MockURLRequestDelegate
+    : public net::URLRequest::Delegate {
  public:
   MockURLRequestDelegate();
   ~MockURLRequestDelegate() override;