Use --build-id link flag in unofficial builds

The sampling profiler expects build ids to be present in Chrome's
modules. Enabling in unofficial builds permits testing its behavior on
the commit queue.

Bug: 870919
Change-Id: I08c69070155ff572a63fc1e1f8959e6c308a8569
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2236753Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Mike Wittman <wittman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#776312}

build/config/compiler/BUILD.gn

@@ -121,9 +121,6 @@ declare_args() {
   thin_lto_enable_optimizations =
       (is_chromeos || is_android || is_win) && is_official_build
 
-  # By default only the binaries in official builds get build IDs.
-  force_local_build_id = false
-
   # Initialize all local variables with a pattern. This flag will fill
   # uninitialized floating-point types (and 32-bit pointers) with 0xFF and the
   # rest with 0xAA. This makes behavior of uninitialized memory bugs consistent,
@@ -332,14 +329,16 @@ config("compiler") {
       }
     }
 
-    if (is_official_build || force_local_build_id) {
-      # Explicitly pass --build-id to ld. Compilers used to always pass this
-      # implicitly but don't any more (in particular clang when built without
-      # ENABLE_LINKER_BUILD_ID=ON). The crash infrastructure does need a build
-      # id, so explicitly enable it in official builds. It's not needed in
-      # unofficial builds and computing it does slow down the link, so go with
-      # faster links in unofficial builds.
+    # Explicitly pass --build-id to ld. Compilers used to always pass this
+    # implicitly but don't any more (in particular clang when built without
+    # ENABLE_LINKER_BUILD_ID=ON).
+    if (is_official_build) {
+      # The sha1 build id has lower risk of collision but is more expensive to
+      # compute, so only use it in the official build to avoid slowing down
+      # links.
       ldflags += [ "-Wl,--build-id=sha1" ]
+    } else {
+      ldflags += [ "-Wl,--build-id" ]
     }
 
     if (!is_android) {