Move core/fpdfapi/fpdf_page to core/fpdfapi/page

BUG=pdfium:603

Review-Url: https://codereview.chromium.org/2386423004
diff --git a/fpdfsdk/fpdf_flatten.cpp b/fpdfsdk/fpdf_flatten.cpp
index 58a37d2..2eac4e9 100644
--- a/fpdfsdk/fpdf_flatten.cpp
+++ b/fpdfsdk/fpdf_flatten.cpp
@@ -8,13 +8,13 @@
 
 #include <algorithm>
 
-#include "core/fpdfapi/fpdf_page/cpdf_page.h"
-#include "core/fpdfapi/fpdf_page/cpdf_pageobject.h"
 #include "core/fpdfapi/fpdf_parser/cpdf_array.h"
 #include "core/fpdfapi/fpdf_parser/cpdf_document.h"
 #include "core/fpdfapi/fpdf_parser/cpdf_number.h"
 #include "core/fpdfapi/fpdf_parser/cpdf_stream.h"
 #include "core/fpdfapi/fpdf_parser/cpdf_stream_acc.h"
+#include "core/fpdfapi/page/cpdf_page.h"
+#include "core/fpdfapi/page/cpdf_pageobject.h"
 #include "core/fpdfdoc/cpdf_annot.h"
 #include "fpdfsdk/fsdk_define.h"