Add third_party/dragonbox dependency

V8 adds a new dependency to the dragonbox library in
https://crrev.com/c/6395060. Add this dependency for PDFium as well.

Change-Id: Iea04b5e954907f2fdf0285846c845cfb8717eb56
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/132090
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Andy Phan <andyphan@chromium.org>

.gitignore

diff --git a/.gitignore b/.gitignore
index 846ec7f..87a0a29 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,6 +11,7 @@
 /third_party/clang-format
 /third_party/cpu_features/src
 /third_party/depot_tools
+/third_party/dragonbox/src
 /third_party/fast_float/src
 /third_party/fp16/src
 /third_party/freetype/src

DEPS

diff --git a/DEPS b/DEPS
index aca1c4a..e6eebab 100644
--- a/DEPS
+++ b/DEPS
@@ -108,6 +108,10 @@
   # and whatever else without interference from each other.
   'depot_tools_revision': '1fcc527019d786502b02f71b8b764ee674a40953',
   # Three lines of non-changing comments so that
+  # the commit queue can handle CLs rolling dragonbox
+  # and whatever else without interference from each other.
+  'dragonbox_revision': '6c7c925b571d54486b9ffae8d9d18a822801cbda',
+  # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling fast_float
   # and whatever else without interference from each other.
   'fast_float_revision': 'cb1d42aaa1e14b09e1452cfdef373d051b8c02a4',
@@ -350,6 +354,12 @@
     Var('chromium_git') + '/chromium/tools/depot_tools.git@' +
         Var('depot_tools_revision'),
 
+  'third_party/dragonbox/src': {
+    'url': Var('chromium_git') + '/external/github.com/jk-jeon/dragonbox.git@' +
+        Var('dragonbox_revision'),
+    'condition': 'checkout_v8',
+  },
+
   'third_party/fast_float/src':
     Var('chromium_git') + '/external/github.com/fastfloat/fast_float.git@' +
         Var('fast_float_revision'),

third_party/dragonbox/BUILD.gn

diff --git a/third_party/dragonbox/BUILD.gn b/third_party/dragonbox/BUILD.gn
new file mode 100644
index 0000000..981be5b
--- /dev/null
+++ b/third_party/dragonbox/BUILD.gn
@@ -0,0 +1,16 @@
+# Copyright 2025 The PDFium Authors
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+config("dragonbox_config") {
+  include_dirs = [ "src/include" ]
+}
+
+source_set("dragonbox") {
+  public = [ "src/include/dragonbox/dragonbox.h" ]
+
+  configs -= [ "//build/config/compiler:chromium_code" ]
+  configs += [ "//build/config/compiler:no_chromium_code" ]
+
+  public_configs = [ ":dragonbox_config" ]
+}

third_party/dragonbox/README.pdfium

diff --git a/third_party/dragonbox/README.pdfium b/third_party/dragonbox/README.pdfium
new file mode 100644
index 0000000..1b62483
--- /dev/null
+++ b/third_party/dragonbox/README.pdfium
@@ -0,0 +1,15 @@
+Name: dragonbox
+URL: https://github.com/jk-jeon/dragonbox
+Version: 1.1.3
+Revision: 6c7c925b571d54486b9ffae8d9d18a822801cbda
+License: Apache-with-LLVM-Exception, BSL-1.0
+License File: src/LICENSE-Apache2-LLVM, src/LICENSE-Boost
+Shipped: yes
+Security Critical: yes
+CPEPrefix: unknown
+
+Description:
+A fast float-to-string conversion algorithm.
+
+Local Modifications:
+None