Add share_target field to Manifest.

content/renderer/manifest/manifest_uma_util.cc

Index: content/renderer/manifest/manifest_uma_util.cc
diff --git a/content/renderer/manifest/manifest_uma_util.cc b/content/renderer/manifest/manifest_uma_util.cc
index 4a0a0f142eb8d4c071a589043991349930ce3562..a7ffd3f54dd966fb6c5e3b0c5dfe230aa8f6b83d 100644
--- a/content/renderer/manifest/manifest_uma_util.cc
+++ b/content/renderer/manifest/manifest_uma_util.cc
@@ -44,6 +44,8 @@ void ManifestUmaUtil::ParseSucceeded(const Manifest& manifest) {
   UMA_HISTOGRAM_BOOLEAN("Manifest.HasProperty.orientation",
       manifest.orientation != blink::WebScreenOrientationLockDefault);
   UMA_HISTOGRAM_BOOLEAN("Manifest.HasProperty.icons", !manifest.icons.empty());
+  UMA_HISTOGRAM_BOOLEAN("Manifest.HasProperty.share_target",
+                        manifest.share_target.has_value());
   UMA_HISTOGRAM_BOOLEAN("Manifest.HasProperty.gcm_sender_id",
       !manifest.gcm_sender_id.is_null());
 }