Move IPC fuzzer switches and helpers from chrome/common to content/common.

content/common/BUILD.gn

Index: content/common/BUILD.gn
diff --git a/content/common/BUILD.gn b/content/common/BUILD.gn
index 9da27ebaf188159a0b0c0d28084c22b3a3a90f01..bf2644185c6e491a23898e390268b1864f9c2c20 100644
--- a/content/common/BUILD.gn
+++ b/content/common/BUILD.gn
@@ -7,6 +7,7 @@ import("//build/config/ui.gni")
 import("//content/common/common.gni")
 import("//media/media_options.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
+import("//tools/ipc_fuzzer/ipc_fuzzer.gni")
 if (is_mac) {
   import("//build/config/mac/mac_sdk.gni")
 }
@@ -200,6 +201,14 @@ source_set("common") {
       ]
     }
   }
+
+  if (enable_ipc_fuzzer) {
+    configs += [ "//tools/ipc_fuzzer:ipc_fuzzer_config" ]
+    sources += [
+      "external_ipc_dumper.cc",
+      "external_ipc_dumper.h",
+    ]
+  }
 }
 
 # See comment at the top of //content/BUILD.gn for how this works.