Add third_party/nasm to DEPS.

NASM will be used in the near future to build libjpeg-turbo.

Bug: chromium:766721
Change-Id: Ic19e782ad4880edc1faaf85d3e69875c1918b63d
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/68691
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>

DEPS

diff --git a/DEPS b/DEPS
index 19aa624..91f4366 100644
--- a/DEPS
+++ b/DEPS
@@ -77,6 +77,10 @@
   # and whatever else without interference from each other.
   'markupsafe_revision': '8f45f5cfa0009d2a70589bcda0349b8cb2b72783',
   # Three lines of non-changing comments so that
+  # the commit queue can handle CLs rolling nasm_source
+  # and whatever else without interference from each other.
+  'nasm_source_revision': 'c74336e4a09381e77e3ec2e8968a319fefa6e8f7',
+  # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling pdfium_tests
   # and whatever else without interference from each other.
   'pdfium_tests_revision': 'b4e9a126d289b49002d0f0acac71d1fdc26953b3',
@@ -168,6 +172,10 @@
     Var('chromium_git') + '/chromium/src/third_party/markupsafe.git@' +
         Var('markupsafe_revision'),
 
+  'third_party/nasm':
+    Var('chromium_git') + '/chromium/deps/nasm.git@' +
+        Var('nasm_source_revision'),
+
   'third_party/skia':
     Var('chromium_git') + '/skia.git@' +  Var('skia_revision'),