Conditionally set enable_ipc_fuzzer for GN builds.

tools/ipc_fuzzer/ipc_fuzzer.gni

Index: tools/ipc_fuzzer/ipc_fuzzer.gni
diff --git a/tools/ipc_fuzzer/ipc_fuzzer.gni b/tools/ipc_fuzzer/ipc_fuzzer.gni
index 1c7d8ca709920eda67651a1c29f2d8abee558f94..f4f41ac523ed4d226d77639fdf513820d32e4b28 100644
--- a/tools/ipc_fuzzer/ipc_fuzzer.gni
+++ b/tools/ipc_fuzzer/ipc_fuzzer.gni
@@ -2,7 +2,15 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/chrome_build.gni")
+import("//build/config/chromecast_build.gni")
+import("//build/config/sanitizers/sanitizers.gni")
+
 declare_args() {
-  # Don't build IPC fuzzer by default.
-  enable_ipc_fuzzer = false
+  # Build IPC fuzzer by default if it's a supported configuration. For
+  # sanitizer builds, this needs to be enabled explicitly as they can be slow
+  # (especially MSan).
+  enable_ipc_fuzzer =
+      is_clang && !is_component_build && !is_official_build && !is_chromecast &&
+      !using_sanitizer && (is_linux || is_mac || is_win)
 }