Avoid using constexpr char in headers.

https://groups.google.com/a/chromium.org/g/chromium-dev/c/SyIIaptlkrA
says not to do this, so be consistent with Chromium's guidance.

Change-Id: Ib21c9d772ae4c4525bcde1665d6da07fbd983655
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/81631
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>

constants/BUILD.gn

diff --git a/constants/BUILD.gn b/constants/BUILD.gn
index 4489b66..3b3ae2d 100644
--- a/constants/BUILD.gn
+++ b/constants/BUILD.gn
@@ -7,12 +7,17 @@
 source_set("constants") {
   sources = [
     "access_permissions.h",
+    "annotation_common.cpp",
     "annotation_common.h",
     "annotation_flags.h",
+    "form_fields.cpp",
     "form_fields.h",
     "form_flags.h",
+    "page_object.cpp",
     "page_object.h",
+    "stream_dict_common.cpp",
     "stream_dict_common.h",
+    "transparency.cpp",
     "transparency.h",
   ]
 }

constants/annotation_common.cpp

diff --git a/constants/annotation_common.cpp b/constants/annotation_common.cpp
new file mode 100644
index 0000000..40050e2
--- /dev/null
+++ b/constants/annotation_common.cpp
@@ -0,0 +1,37 @@
+// Copyright 2021 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "constants/annotation_common.h"
+
+namespace pdfium {
+namespace annotation {
+
+// PDF 1.7 spec, table 8.15.
+// Entries common to all annotation dictionaries.
+const char kType[] = "Type";
+const char kSubtype[] = "Subtype";
+const char kRect[] = "Rect";
+const char kContents[] = "Contents";
+const char kP[] = "P";
+const char kNM[] = "NM";
+const char kM[] = "M";
+const char kF[] = "F";
+const char kAP[] = "AP";
+const char kAS[] = "AS";
+const char kBorder[] = "Border";
+const char kC[] = "C";
+const char kStructParent[] = "StructParent";
+const char kOC[] = "OC";
+
+// Entries for polygon and polyline annotations.
+const char kVertices[] = "Vertices";
+
+// Entries for ink annotations
+const char kInkList[] = "InkList";
+
+// Entries for line annotations
+const char kL[] = "L";
+
+}  // namespace annotation
+}  // namespace pdfium

constants/annotation_common.h

diff --git a/constants/annotation_common.h b/constants/annotation_common.h
index 656842b..0dfe206 100644
--- a/constants/annotation_common.h
+++ b/constants/annotation_common.h
@@ -8,32 +8,26 @@
 namespace pdfium {
 namespace annotation {
 
-// PDF 1.7 spec, table 8.15.
-// Entries common to all annotation dictionaries.
+extern const char kType[];
+extern const char kSubtype[];
+extern const char kRect[];
+extern const char kContents[];
+extern const char kP[];
+extern const char kNM[];
+extern const char kM[];
+extern const char kF[];
+extern const char kAP[];
+extern const char kAS[];
+extern const char kBorder[];
+extern const char kC[];
+extern const char kStructParent[];
+extern const char kOC[];
 
-constexpr char kType[] = "Type";
-constexpr char kSubtype[] = "Subtype";
-constexpr char kRect[] = "Rect";
-constexpr char kContents[] = "Contents";
-constexpr char kP[] = "P";
-constexpr char kNM[] = "NM";
-constexpr char kM[] = "M";
-constexpr char kF[] = "F";
-constexpr char kAP[] = "AP";
-constexpr char kAS[] = "AS";
-constexpr char kBorder[] = "Border";
-constexpr char kC[] = "C";
-constexpr char kStructParent[] = "StructParent";
-constexpr char kOC[] = "OC";
+extern const char kVertices[];
 
-// Entries for polygon and polyline annotations.
-constexpr char kVertices[] = "Vertices";
+extern const char kInkList[];
 
-// Entries for ink annotations
-constexpr char kInkList[] = "InkList";
-
-// Entries for line annotations
-constexpr char kL[] = "L";
+extern const char kL[];
 
 }  // namespace annotation
 }  // namespace pdfium

constants/form_fields.cpp

diff --git a/constants/form_fields.cpp b/constants/form_fields.cpp
new file mode 100644
index 0000000..7409e8d
--- /dev/null
+++ b/constants/form_fields.cpp
@@ -0,0 +1,30 @@
+// Copyright 2021 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "constants/form_fields.h"
+
+namespace pdfium {
+namespace form_fields {
+
+// PDF 1.7 spec, table 8.69.
+// Entries common to all field dictionaries.
+const char kFT[] = "FT";
+const char kParent[] = "Parent";
+const char kKids[] = "Kids";
+const char kT[] = "T";
+const char kTU[] = "TU";
+const char kTM[] = "TM";
+const char kFf[] = "Ff";
+const char kV[] = "V";
+const char kDV[] = "DV";
+const char kAA[] = "AA";
+
+// FT values from PDF 1.7 spec, table 8.69.
+const char kBtn[] = "Btn";
+const char kTx[] = "Tx";
+const char kCh[] = "Ch";
+const char kSig[] = "Sig";
+
+}  // namespace form_fields
+}  // namespace pdfium

constants/form_fields.h

diff --git a/constants/form_fields.h b/constants/form_fields.h
index 5b7c169..cd2b0fa 100644
--- a/constants/form_fields.h
+++ b/constants/form_fields.h
@@ -8,24 +8,21 @@
 namespace pdfium {
 namespace form_fields {
 
-// PDF 1.7 spec, table 8.69.
-// Entries common to all field dictionaries.
-constexpr char kFT[] = "FT";
-constexpr char kParent[] = "Parent";
-constexpr char kKids[] = "Kids";
-constexpr char kT[] = "T";
-constexpr char kTU[] = "TU";
-constexpr char kTM[] = "TM";
-constexpr char kFf[] = "Ff";
-constexpr char kV[] = "V";
-constexpr char kDV[] = "DV";
-constexpr char kAA[] = "AA";
+extern const char kFT[];
+extern const char kParent[];
+extern const char kKids[];
+extern const char kT[];
+extern const char kTU[];
+extern const char kTM[];
+extern const char kFf[];
+extern const char kV[];
+extern const char kDV[];
+extern const char kAA[];
 
-// FT values from PDF 1.7 spec, table 8.69.
-constexpr char kBtn[] = "Btn";
-constexpr char kTx[] = "Tx";
-constexpr char kCh[] = "Ch";
-constexpr char kSig[] = "Sig";
+extern const char kBtn[];
+extern const char kTx[];
+extern const char kCh[];
+extern const char kSig[];
 
 }  // namespace form_fields
 }  // namespace pdfium

constants/page_object.cpp

diff --git a/constants/page_object.cpp b/constants/page_object.cpp
new file mode 100644
index 0000000..42f76b9
--- /dev/null
+++ b/constants/page_object.cpp
@@ -0,0 +1,24 @@
+// Copyright 2021 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "constants/page_object.h"
+
+namespace pdfium {
+namespace page_object {
+
+// PDF 1.7 spec, table 3.27.
+// Entries in a page object.
+const char kType[] = "Type";
+const char kParent[] = "Parent";
+const char kResources[] = "Resources";
+const char kMediaBox[] = "MediaBox";
+const char kCropBox[] = "CropBox";
+const char kBleedBox[] = "BleedBox";
+const char kTrimBox[] = "TrimBox";
+const char kArtBox[] = "ArtBox";
+const char kContents[] = "Contents";
+const char kRotate[] = "Rotate";
+
+}  // namespace page_object
+}  // namespace pdfium

constants/page_object.h

diff --git a/constants/page_object.h b/constants/page_object.h
index 8a41b8c..75f9b76 100644
--- a/constants/page_object.h
+++ b/constants/page_object.h
@@ -8,19 +8,16 @@
 namespace pdfium {
 namespace page_object {
 
-// PDF 1.7 spec, table 3.27.
-// Entries in a page object.
-
-constexpr char kType[] = "Type";
-constexpr char kParent[] = "Parent";
-constexpr char kResources[] = "Resources";
-constexpr char kMediaBox[] = "MediaBox";
-constexpr char kCropBox[] = "CropBox";
-constexpr char kBleedBox[] = "BleedBox";
-constexpr char kTrimBox[] = "TrimBox";
-constexpr char kArtBox[] = "ArtBox";
-constexpr char kContents[] = "Contents";
-constexpr char kRotate[] = "Rotate";
+extern const char kType[];
+extern const char kParent[];
+extern const char kResources[];
+extern const char kMediaBox[];
+extern const char kCropBox[];
+extern const char kBleedBox[];
+extern const char kTrimBox[];
+extern const char kArtBox[];
+extern const char kContents[];
+extern const char kRotate[];
 
 }  // namespace page_object
 }  // namespace pdfium

constants/stream_dict_common.cpp

diff --git a/constants/stream_dict_common.cpp b/constants/stream_dict_common.cpp
new file mode 100644
index 0000000..0f9ca30
--- /dev/null
+++ b/constants/stream_dict_common.cpp
@@ -0,0 +1,22 @@
+// Copyright 2021 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "constants/stream_dict_common.h"
+
+namespace pdfium {
+namespace stream {
+
+// PDF 1.7 spec, table 3.4.
+// Entries common to all stream dictionaries.
+//
+// TODO(https://crbug.com/pdfium/1049): Examine all usages of "Length",
+// "Filter", and "F".
+const char kLength[] = "Length";
+const char kFilter[] = "Filter";
+const char kDecodeParms[] = "DecodeParms";
+const char kF[] = "F";
+const char kDL[] = "DL";
+
+}  // namespace stream
+}  // namespace pdfium

constants/stream_dict_common.h

diff --git a/constants/stream_dict_common.h b/constants/stream_dict_common.h
index fc12622..d9f6bd9 100644
--- a/constants/stream_dict_common.h
+++ b/constants/stream_dict_common.h
@@ -8,18 +8,11 @@
 namespace pdfium {
 namespace stream {
 
-// PDF 1.7 spec, table 3.4.
-// Entries common to all stream dictionaries.
-
-// TODO(https://crbug.com/pdfium/1049): Examine all usages of "Length",
-// "Filter", and "F".
-constexpr char kLength[] = "Length";
-constexpr char kFilter[] = "Filter";
-constexpr char kDecodeParms[] = "DecodeParms";
-constexpr char kF[] = "F";
-// constexpr char kFFilter[] = "FFilter";
-// constexpr char kFDecodeParms[] = "FDecodeParms";
-constexpr char kDL[] = "DL";
+extern const char kLength[];
+extern const char kFilter[];
+extern const char kDecodeParms[];
+extern const char kF[];
+extern const char kDL[];
 
 }  // namespace stream
 }  // namespace pdfium

constants/transparency.cpp

diff --git a/constants/transparency.cpp b/constants/transparency.cpp
new file mode 100644
index 0000000..dc2405a
--- /dev/null
+++ b/constants/transparency.cpp
@@ -0,0 +1,48 @@
+// Copyright 2021 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "constants/transparency.h"
+
+namespace pdfium {
+namespace transparency {
+
+// PDF 1.7 spec, table 7.2.
+// Standard separable blend modes.
+const char kNormal[] = "Normal";
+const char kMultiply[] = "Multiply";
+const char kScreen[] = "Screen";
+const char kOverlay[] = "Overlay";
+const char kDarken[] = "Darken";
+const char kLighten[] = "Lighten";
+const char kColorDodge[] = "ColorDodge";
+const char kColorBurn[] = "ColorBurn";
+const char kHardLight[] = "HardLight";
+const char kSoftLight[] = "SoftLight";
+const char kDifference[] = "Difference";
+const char kExclusion[] = "Exclusion";
+
+// PDF 1.7 spec, table 7.3.
+// Standard nonseparable blend modes.
+const char kHue[] = "Hue";
+const char kSaturation[] = "Saturation";
+const char kColor[] = "Color";
+const char kLuminosity[] = "Luminosity";
+
+// PDF 1.7 spec, table 7.10.
+// Entries in a soft-mask dictionary.
+const char kSoftMaskSubType[] = "S";
+const char kAlpha[] = "Alpha";
+const char kG[] = "G";
+const char kBC[] = "BC";
+const char kTR[] = "TR";
+
+// PDF 1.7 spec, table 7.13.
+// Additional entries specific to a transparency group attributes dictionary.
+const char kGroupSubType[] = "S";
+const char kTransparency[] = "Transparency";
+const char kCS[] = "CS";
+const char kI[] = "I";
+
+}  // namespace transparency
+}  // namespace pdfium

constants/transparency.h

diff --git a/constants/transparency.h b/constants/transparency.h
index 6532868..87a2408 100644
--- a/constants/transparency.h
+++ b/constants/transparency.h
@@ -8,46 +8,34 @@
 namespace pdfium {
 namespace transparency {
 
-// PDF 1.7 spec, table 7.2.
-// Standard separable blend modes.
+extern const char kNormal[];
+extern const char kMultiply[];
+extern const char kScreen[];
+extern const char kOverlay[];
+extern const char kDarken[];
+extern const char kLighten[];
+extern const char kColorDodge[];
+extern const char kColorBurn[];
+extern const char kHardLight[];
+extern const char kSoftLight[];
+extern const char kDifference[];
+extern const char kExclusion[];
 
-constexpr char kNormal[] = "Normal";
-constexpr char kMultiply[] = "Multiply";
-constexpr char kScreen[] = "Screen";
-constexpr char kOverlay[] = "Overlay";
-constexpr char kDarken[] = "Darken";
-constexpr char kLighten[] = "Lighten";
-constexpr char kColorDodge[] = "ColorDodge";
-constexpr char kColorBurn[] = "ColorBurn";
-constexpr char kHardLight[] = "HardLight";
-constexpr char kSoftLight[] = "SoftLight";
-constexpr char kDifference[] = "Difference";
-constexpr char kExclusion[] = "Exclusion";
+extern const char kHue[];
+extern const char kSaturation[];
+extern const char kColor[];
+extern const char kLuminosity[];
 
-// PDF 1.7 spec, table 7.3.
-// Standard nonseparable blend modes.
+extern const char kSoftMaskSubType[];
+extern const char kAlpha[];
+extern const char kG[];
+extern const char kBC[];
+extern const char kTR[];
 
-constexpr char kHue[] = "Hue";
-constexpr char kSaturation[] = "Saturation";
-constexpr char kColor[] = "Color";
-constexpr char kLuminosity[] = "Luminosity";
-
-// PDF 1.7 spec, table 7.10.
-// Entries in a soft-mask dictionary.
-
-constexpr char kSoftMaskSubType[] = "S";
-constexpr char kAlpha[] = "Alpha";
-constexpr char kG[] = "G";
-constexpr char kBC[] = "BC";
-constexpr char kTR[] = "TR";
-
-// PDF 1.7 spec, table 7.13.
-// Additional entries specific to a transparency group attributes dictionary.
-
-constexpr char kGroupSubType[] = "S";
-constexpr char kTransparency[] = "Transparency";
-constexpr char kCS[] = "CS";
-constexpr char kI[] = "I";
+extern const char kGroupSubType[];
+extern const char kTransparency[];
+extern const char kCS[];
+extern const char kI[];
 
 }  // namespace transparency
 }  // namespace pdfium