[inspector] Build inspector under v8_enable_inspector build flag.

build_overrides/v8.gni

 # Copyright 2015 The V8 project authors. All rights reserved.
 # 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")
 import("//build/config/ui.gni")
 import("//build/config/v8_target_cpu.gni")
 import("//gni/v8.gni")
 
 if (is_android) {
   import("//build/config/android/config.gni")
 }
 
-if (((v8_current_cpu == "x86" ||
-      v8_current_cpu == "x64" ||
-      v8_current_cpu=="x87") &&
-     (is_linux || is_mac)) ||
+if (((v8_current_cpu == "x86" || v8_current_cpu == "x64" ||
+      v8_current_cpu == "x87") && (is_linux || is_mac)) ||
     (v8_current_cpu == "ppc64" && is_linux)) {
   v8_enable_gdbjit_default = true
 }
 
 v8_imminent_deprecation_warnings_default = true
 
 # Add simple extras solely for the purpose of the cctests.
 v8_extra_library_files = [ "//test/cctest/test-extra.js" ]
-v8_experimental_extra_library_files = [ "//test/cctest/test-experimental-extra.js" ]
+v8_experimental_extra_library_files =
+    [ "//test/cctest/test-experimental-extra.js" ]
+
+declare_args() {
+  # Enable inspector. See include/v8-inspector.h.
+  v8_enable_inspector = false
+}
+
+v8_enable_inspector_override = v8_enable_inspector

[Michael Achenbach, 2016/09/02 07:21:28]

The last line should land in chromium's v8.gni first with a chromium default.

[dgozman, 2016/09/02 14:05:59]

Sure! I want to get a review of this patch first though, so that everyone
interested is fine with the plan.