Remove enable_pattern_initialization

Pattern initialization has been turned on by http://crrev.com/c/2067928
for Linux, therefore enabled on ChromeOS. There is no need of this
variable any more.

Bug: 1042451
Change-Id: I30aa3a82ab56dac09f7d41fc0ad8cfed4c43f204
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2070972Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Tiancong Wang <tcwang@google.com>
Commit-Queue: Jian Cai <jiancai@google.com>
Cr-Commit-Position: refs/heads/master@{#744362}

build/config/chromeos/BUILD.gn

@@ -11,9 +11,6 @@ declare_args() {
   # https://research.fb.com/wp-content/uploads/2017/01/cgo2017-hfsort-final1.pdf?
   # to a file, used for generating orderfiles in Chrome OS
   dump_call_chain_clustering_order = ""
-
-  # Enable pattern initialization. Disabled by default. http://crbug.com/966551
-  enable_pattern_initialization = false
 }
 
 declare_args() {
@@ -34,8 +31,4 @@ config("compiler") {
     cflags = [ "-fexperimental-new-pass-manager" ]
     ldflags = [ "-fexperimental-new-pass-manager" ]
   }
-
-  if (enable_pattern_initialization) {
-    cflags = [ "-ftrivial-auto-var-init=pattern" ]
-  }
 }