Decouple use_system_harfbuzz=1 from is_chromeos=1 & is_linux build flags

third_party/harfbuzz-ng/harfbuzz.gyp

Index: third_party/harfbuzz-ng/harfbuzz.gyp
diff --git a/third_party/harfbuzz-ng/harfbuzz.gyp b/third_party/harfbuzz-ng/harfbuzz.gyp
index b9be8ae2f6c4789e15f540bcf7636ea3eb085c79..2a5b5e5d770d32c68e8efde9f973738cc4ea8598 100644
--- a/third_party/harfbuzz-ng/harfbuzz.gyp
+++ b/third_party/harfbuzz-ng/harfbuzz.gyp
@@ -7,17 +7,16 @@
     '../../build/win_precompile.gypi',
   ],
   'variables': {
-    'conditions': [
-      ['OS=="linux" and chromeos==1', {
-        # Since version 1.31.0, pangoft2 which we depend on pulls in harfbuzz
-        # anyways. However, we want to have control of the version of harfbuzz
-        # we use, so don't use system harfbuzz unless we are building for
-        # chrome os, where we have the system harfbuzz under control.
-        'use_system_harfbuzz%': '<!(python ../../build/check_return_value.py <(pkg-config) --atleast-version=1.31.0 pangoft2)',
-      }, {
-        'use_system_harfbuzz': 0,
-      }],
-    ],
+        # Only overriden by the official Chromium OS builds which are done
+        # against the Chromium OS SDK in a chroot. Should not be needed in any
+        # other configuration.
+        # We need to be controlling the version of HarfBuzz used by Blink, as
+        # the correctness and good performance of text processing is only
+        # guaranteed and supported against the version of HarfBuzz that is in
+        # third_party/harfbuzz-ng.  So, on all other platforms HarfBuzz is
+        # statically linked, on Chrome OS it is controlled as well, but part
+        # of the system.
+        'use_system_harfbuzz%': 0,
   },
   'conditions': [
     ['use_system_harfbuzz==0', {