Handle the "debug_devtools" build arg in GN builds

chrome/browser/devtools/BUILD.gn

Index: chrome/browser/devtools/BUILD.gn
diff --git a/chrome/browser/devtools/BUILD.gn b/chrome/browser/devtools/BUILD.gn
index 9404d4bdf6248eeb328a871c634bfbcf3d7905f4..9bf5a253507cb1a0a3c1e3c9af66768efedda5a4 100644
--- a/chrome/browser/devtools/BUILD.gn
+++ b/chrome/browser/devtools/BUILD.gn
@@ -2,6 +2,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/features.gni")
+
 action("devtools_protocol_constants") {
   script = "//content/public/browser/devtools_protocol_constants_generator.py"
 
@@ -21,6 +23,8 @@ action("devtools_protocol_constants") {
 
 # GYP version: chrome/chrome_debugger.gypi:debugger
 static_library("devtools") {
+  defines = []
+
   # Note: new sources and deps should be generally added in (!is_android) below.
   sources = [
     "devtools_network_conditions.cc",
@@ -40,12 +44,10 @@ static_library("devtools") {
   ]
   sources += get_target_outputs(":devtools_protocol_constants")
 
-  # TODO(GYP)
-  #     ['debug_devtools==1', {
-  #       'defines': [
-  #         'DEBUG_DEVTOOLS=1',
-  #        ],
-  #     }],
+  if (debug_devtools) {
+    defines += [ "DEBUG_DEVTOOLS=1" ]

[brettw, 2014/09/25 20:40:53]

It would be nice to have a config somewhere that defines this so we don't need
to hardcode the name in several places. I notice there is an existing one in
chrome/browser/ui/BUILD.gn

It looks like WebKit also needs to be checked (not sure if you already did this
or knew about it). I see at least one "debug_devtools = false" in a file there
with a TODO.

Can we have a config in blink (since it defines what devtools are) that does
this, and then set that config on targets that need this value?

configs += [ "//third_party/WebKit/public:debug_devtools" ]
or something.

[apavlov, 2014/09/26 07:10:27]

Good point. I've got https://codereview.chromium.org/608523002/ where I fix the
Blink part. I've added you to the R list and created the "debug_devtools" config
as you suggest. Please take a look, as that should be landed first.

+  }
+
   if (is_win) {
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     cflags = [ "/wd4267" ]