Create chrome_branch_deps.json for branch 6421.

Change-Id: I7b8cfea1816bc0ec1ed9e929221a07b850aec7b7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5453637
Bot-Commit: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/branch-heads/6421@{#1}
Cr-Branched-From: 0f4fe5592063b3c6fe88f7bcf5fde5644932d17e-refs/heads/main@{#1287225}
diff --git a/chrome/chrome_branch_deps.json b/chrome/chrome_branch_deps.json
new file mode 100644
index 0000000..b1721c2
--- /dev/null
+++ b/chrome/chrome_branch_deps.json
@@ -0,0 +1,16 @@
+{
+  "src": "refs/branch-heads/6421",
+  "src:src/clank": "refs/heads/chromium/6421",
+  "src:src/internal": "refs/heads/chromium/6421",
+  "src:src/ios_internal": "refs/heads/chromium/6421",
+  "src:src/third_party/angle": "refs/heads/chromium/6421",
+  "src:src/third_party/dawn": "refs/heads/chromium/6421",
+  "src:src/third_party/devtools-frontend-internal": "refs/heads/chromium/6421",
+  "src:src/third_party/devtools-frontend-internal:devtools-frontend": "refs/heads/chromium/6421",
+  "src:src/third_party/devtools-frontend/src": "refs/heads/chromium/6421",
+  "src:src/third_party/instrumented_libs": "refs/heads/chromium/6421",
+  "src:src/third_party/pdfium": "refs/heads/chromium/6421",
+  "src:src/third_party/vulkan-deps": "refs/heads/chromium/6421",
+  "src:src/third_party/webrtc": "refs/branch-heads/6421",
+  "src:src/v8": "refs/heads/chromium/6421"
+}