Install CIPD ninja using DEPS

See chromium/src's CL https://crrev.com/c/3869740 for the context.

Bug: chromium:1340825
Change-Id: I4429bc7a2a1e57f559c4c958234ce150842448df
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/104340
Commit-Queue: Junji Watanabe <jwata@google.com>
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Austin Eng <enga@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>

.gitignore

@@ -22,6 +22,7 @@
 /third_party/jsoncpp
 /third_party/llvm-build
 /third_party/markupsafe
+/third_party/ninja
 /third_party/node
 /third_party/node-addon-api
 /third_party/node-api-headers

DEPS

@@ -17,6 +17,9 @@ vars = {
   'dawn_cmake_version': 'version:2@3.23.3',
   'dawn_cmake_win32_sha1': 'b106d66bcdc8a71ea2cdf5446091327bfdb1bcd7',
   'dawn_gn_version': 'git_revision:bd99dbf98cbdefe18a4128189665c5761263bcfb',
+  # ninja CIPD package version.
+  # https://chrome-infra-packages.appspot.com/p/infra/3pp/tools/ninja
+  'dawn_ninja_version': 'version:2@1.8.2.chromium.3',
   'dawn_go_version': 'version:2@1.18.4',
 
   'node_darwin_arm64_sha': '31859fc1fa0994a95f44f09c367d6ff63607cfde',
@@ -190,6 +193,16 @@ deps = {
     'dep_type': 'cipd',
   },
 
+  'third_party/ninja': {
+    'packages': [
+      {
+        'package': 'infra/3pp/tools/ninja/${{platform}}',
+        'version': Var('dawn_ninja_version'),
+      }
+    ],
+    'dep_type': 'cipd',
+  },
+
   # Misc dependencies inherited from Tint
   'third_party/benchmark': {
     'url': '{chromium_git}/external/github.com/google/benchmark.git@e991355c02b93fe17713efe04cbc2e278e00fdbd',