android_webview: Enable FDO support for some targets.

android_webview/libwebviewchromium.gypi

Index: android_webview/libwebviewchromium.gypi
diff --git a/android_webview/libwebviewchromium.gypi b/android_webview/libwebviewchromium.gypi
index c3259b35905cd6b8f1446e6235da8424204315b9..c6df5494358eef2a734d149a5d6175e47a872f33 100644
--- a/android_webview/libwebviewchromium.gypi
+++ b/android_webview/libwebviewchromium.gypi
@@ -31,6 +31,11 @@
         '../ui/android/ui_android.gyp:page_transition_types_java',
         '../ui/android/ui_android.gyp:window_open_disposition_java',
       ],
+      # Enable feedback-directed optimisation for the library when building in
+      # android.
+      'aosp_build_settings': {
+        'LOCAL_FDO_SUPPORT': 'true',
+      },
     }],
     [ 'android_webview_build==1 and use_system_skia==0', {
       # When not using the system skia there are linker warnings about