DevTools: split protocol.json into files per domain.

content/browser/devtools/BUILD.gn

Index: content/browser/devtools/BUILD.gn
diff --git a/content/browser/devtools/BUILD.gn b/content/browser/devtools/BUILD.gn
index 595f94ffce31e75b10cfa74169a685ae19a8cb0d..da789a4a217f4b7fb1f8da752577ba4a2021c18a 100644
--- a/content/browser/devtools/BUILD.gn
+++ b/content/browser/devtools/BUILD.gn
@@ -36,11 +36,13 @@ grit("devtools_resources") {
 
 action("gen_devtools_protocol_handler") {
   visibility = [ "//content/browser" ]
-
+  deps = [
+    "//third_party/WebKit/Source/core/inspector:protocol_version",
+  ]
   script = "//content/browser/devtools/protocol/" +
            "devtools_protocol_handler_generator.py"
 
-  blink_protocol = "//third_party/WebKit/Source/devtools/protocol.json"
+  blink_protocol = "$root_gen_dir/blink/core/inspector/protocol.json"
   browser_protocol = "browser_protocol.json"
   inputs = [
     blink_protocol,