Do IWYU for <ostream>

Change-Id: Ib20b30bb2d7d289c7b1fbdec110e55edf0a29cf6
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/56130
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
diff --git a/core/fpdfapi/edit/cpdf_pagecontentgenerator.cpp b/core/fpdfapi/edit/cpdf_pagecontentgenerator.cpp
index d013fdb..4f13434 100644
--- a/core/fpdfapi/edit/cpdf_pagecontentgenerator.cpp
+++ b/core/fpdfapi/edit/cpdf_pagecontentgenerator.cpp
@@ -8,6 +8,7 @@
 
 #include <map>
 #include <memory>
+#include <ostream>
 #include <set>
 #include <tuple>
 #include <utility>
diff --git a/core/fxcrt/bytestring.h b/core/fxcrt/bytestring.h
index aff96ed..f221d25 100644
--- a/core/fxcrt/bytestring.h
+++ b/core/fxcrt/bytestring.h
@@ -9,6 +9,7 @@
 
 #include <functional>
 #include <iterator>
+#include <ostream>
 #include <sstream>
 #include <utility>
 
diff --git a/core/fxcrt/fx_coordinates.h b/core/fxcrt/fx_coordinates.h
index d6e1a05..a071693 100644
--- a/core/fxcrt/fx_coordinates.h
+++ b/core/fxcrt/fx_coordinates.h
@@ -13,6 +13,10 @@
 #include "core/fxcrt/fx_system.h"
 #include "third_party/base/numerics/safe_math.h"
 
+#ifndef NDEBUG
+#include <ostream>
+#endif
+
 template <class BaseType>
 class CFX_PTemplate {
  public:
diff --git a/core/fxcrt/widestring.h b/core/fxcrt/widestring.h
index 15c6e8c..e962de3 100644
--- a/core/fxcrt/widestring.h
+++ b/core/fxcrt/widestring.h
@@ -9,6 +9,7 @@
 
 #include <functional>
 #include <iterator>
+#include <ostream>
 #include <utility>
 
 #include "core/fxcrt/fx_system.h"