Return WebView to 32-bit by default.

Bug: 1119325
Change-Id: I04727f349d0012a4a89ab93032530ccecf53e767
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2364210Reviewed-by: Richard Coles <torne@chromium.org>
Commit-Queue: Ben Mason <benmason@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799739}

android_webview/nonembedded/BUILD.gn

@@ -190,7 +190,6 @@ jinja_template("trichrome_webview_manifest") {
   variables = trichrome_jinja_variables + _webview_jinja_variables
   if (android_64bit_target_cpu) {
     variables += [
-      "use32bitAbi=",
       "library=libmonochrome_64.so",
       "trichrome_version=$trichrome_64_32_version_code",
     ]