Add blimp to root GN check_targets

blimp/client/session/assignment_source.h

Index: blimp/client/session/assignment_source.h
diff --git a/blimp/client/session/assignment_source.h b/blimp/client/session/assignment_source.h
index a5ab358c7bc3411e3d6269e5f1a210167f2bcf8a..6999337972074afaccd060c65ec62dc63bb134d1 100644
--- a/blimp/client/session/assignment_source.h
+++ b/blimp/client/session/assignment_source.h
@@ -9,7 +9,6 @@
 
 #include "base/callback.h"
 #include "base/memory/weak_ptr.h"
-#include "blimp/client/blimp_client_export.h"
 #include "net/base/ip_endpoint.h"
 #include "net/url_request/url_fetcher_delegate.h"
 #include "url/gurl.h"
@@ -34,7 +33,7 @@ const char kDummyClientToken[] = "MyVoiceIsMyPassport";
 
 // An Assignment contains the configuration data needed for a client
 // to connect to the engine.
-struct BLIMP_CLIENT_EXPORT Assignment {
+struct Assignment {
   enum TransportProtocol {
     UNKNOWN = 0,
     SSL = 1,
@@ -64,7 +63,7 @@ struct BLIMP_CLIENT_EXPORT Assignment {
 
 // AssignmentSource provides functionality to find out how a client should
 // connect to an engine.
-class BLIMP_CLIENT_EXPORT AssignmentSource : public net::URLFetcherDelegate {
+class AssignmentSource : public net::URLFetcherDelegate {
  public:
   // A Java counterpart will be generated for this enum.
   // GENERATED_JAVA_ENUM_PACKAGE: org.chromium.blimp.assignment