Use the orderfile to build libwebviewchromium.

Use the chrome_orderfile_config config for libwebviewchromium (as is
already done for the WebView-only variants of libmonochrome) so that we
get the same benefit from orderfile optimisation in this build variant.

Bug: 1101454
Change-Id: I7accacb50b988065060517e7ec67eba9107a03b0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2486120Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Benoit L <lizeb@chromium.org>
Commit-Queue: Richard Coles <torne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825417}

android_webview/BUILD.gn

@@ -280,7 +280,10 @@ template("libwebviewchromium_tmpl") {
       "//third_party/blink/public:blink",
     ]
     configs -= [ "//build/config/android:hide_all_but_jni_onload" ]
-    configs += [ "//build/config/android:hide_all_but_jni" ]
+    configs += [
+      "//build/config/android:hide_all_but_jni",
+      "//build/config/compiler:chrome_orderfile_config",
+    ]
   }
 }