Continue splitting pageint.h into per-class files

Add cpdf_streamparser.h and cpdf_contentparser.h since there are
already corresponding .cpp files with the same name.

Review-Url: https://codereview.chromium.org/2521123003
diff --git a/testing/libfuzzer/pdf_streamparser_fuzzer.cc b/testing/libfuzzer/pdf_streamparser_fuzzer.cc
index 277acc0..5cfa318 100644
--- a/testing/libfuzzer/pdf_streamparser_fuzzer.cc
+++ b/testing/libfuzzer/pdf_streamparser_fuzzer.cc
@@ -5,7 +5,7 @@
 #include <cstdint>
 #include <memory>
 
-#include "core/fpdfapi/page/pageint.h"
+#include "core/fpdfapi/page/cpdf_streamparser.h"
 #include "core/fpdfapi/parser/cpdf_object.h"
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {