Move SafeBrowsing files from //chrome/browser to a separate target.

BUG=

Review-Url: https://codereview.chromium.org/2940403002
Cr-Original-Commit-Position: refs/heads/master@{#481019}
Committed: https://chromium.googlesource.com/chromium/src/+/e4da0e76b5b75d453fec094f62ad06659e66708e
Review-Url: https://codereview.chromium.org/2940403002
Cr-Commit-Position: refs/heads/master@{#481081}
diff --git a/chrome/browser/extensions/BUILD.gn b/chrome/browser/extensions/BUILD.gn
index 746767ab..0dd2a76c 100644
--- a/chrome/browser/extensions/BUILD.gn
+++ b/chrome/browser/extensions/BUILD.gn
@@ -817,6 +817,7 @@
     "//chrome/browser/devtools",
     "//chrome/browser/media/router",
     "//chrome/browser/media/router/discovery",
+    "//chrome/browser/safe_browsing",
     "//chrome/common",
     "//chrome/common/extensions:mojo_bindings",
     "//chrome/common/extensions/api:api_registration",