Disable PGO for the official builds (for Dev branch!)

This CL will be merged to the Dev branch for the PGO experiment, it's
not supposed to land on trunk.

Bug: 1060025
Change-Id: I7546317c759292c1b3d0f6b50b4c9f6c836c20a4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2185587
Reviewed-by: Krishna Govind <govind@chromium.org>
Reviewed-by: Sébastien Marchand <sebmarchand@chromium.org>
Cr-Commit-Position: refs/branch-heads/4137@{#6}
Cr-Branched-From: e5d162f-refs/heads/master@{#765837}

build/config/compiler/pgo/pgo.gni

@@ -9,9 +9,6 @@ declare_args() {
   #     1 : Used during the PGI (instrumentation) phase.
   #     2 : Used during the PGO (optimization) phase.
   chrome_pgo_phase = 0
-  if (is_official_build && (is_win || is_mac)) {
-    chrome_pgo_phase = 2
-  }
 
   # When using chrome_pgo_phase = 2, read profile data from this path.
   pgo_data_path = ""