Add provider type "ON_DEVICE_HEAD" for on device head suggest.

Result from on device head will be set as [AutocompleteProviderType::TYPE_ON_DEVICE_HEAD|AutocompleteMatchType::SEARCH_SUGGEST|subtype_identifier=271].

Bug: 925072
Change-Id: Iac72e0df2ab03bb331efab68b71a2f9e26f81eee
Reviewed-on: https://chromium-review.googlesource.com/c/1484502
Commit-Queue: Ce Chen <cch@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#635799}

components/omnibox/browser/autocomplete_controller.cc

@@ -64,16 +64,24 @@ void AutocompleteMatchToAssistedQuery(
   // Default value, indicating no subtype.
   *subtype = base::string16::npos;
 
-  // If provider is TYPE_ZERO_SUGGEST, set the subtype accordingly.
-  // Type will be set in the switch statement below where we'll enter one of
-  // SEARCH_SUGGEST or NAVSUGGEST. This subtype indicates context-aware zero
-  // suggest.
-  if (provider &&
-      (provider->type() == AutocompleteProvider::TYPE_ZERO_SUGGEST) &&
-      (match != AutocompleteMatchType::SEARCH_SUGGEST_PERSONALIZED)) {
-    DCHECK((match == AutocompleteMatchType::SEARCH_SUGGEST) ||
-           (match == AutocompleteMatchType::NAVSUGGEST));
-    *subtype = 66;
+  // If provider is TYPE_ZERO_SUGGEST or TYPE_ON_DEVICE_HEAD, set the subtype
+  // accordingly. Type will be set in the switch statement below where we'll
+  // enter one of SEARCH_SUGGEST or NAVSUGGEST.
+  if (provider) {
+    if (provider->type() == AutocompleteProvider::TYPE_ZERO_SUGGEST &&
+        (match != AutocompleteMatchType::SEARCH_SUGGEST_PERSONALIZED)) {
+      DCHECK((match == AutocompleteMatchType::SEARCH_SUGGEST) ||
+             (match == AutocompleteMatchType::NAVSUGGEST));
+      // We abuse this subtype and use it to for zero-suggest suggestions that
+      // aren't personalized by the server. That is, it indicates either
+      // client-side most-likely URL suggestions or server-side suggestions
+      // that depend only on the URL as context.
+      *subtype = 66;
+    } else if (provider->type() == AutocompleteProvider::TYPE_ON_DEVICE_HEAD) {
+      DCHECK(match == AutocompleteMatchType::SEARCH_SUGGEST);
+      // This subtype indicates a match from an on-device head provider.
+      *subtype = 271;
+    }
   }
 
   switch (match) {

components/omnibox/browser/autocomplete_provider.cc

@@ -53,6 +53,8 @@ const char* AutocompleteProvider::TypeToString(Type type) {
       return "ZeroSuggest";
     case TYPE_CLIPBOARD:
       return "Clipboard";
+    case TYPE_ON_DEVICE_HEAD:
+      return "OnDeviceHead";
     default:
       NOTREACHED() << "Unhandled AutocompleteProvider::Type " << type;
       return "Unknown";

components/omnibox/browser/autocomplete_provider.h

@@ -64,6 +64,7 @@ typedef std::vector<metrics::OmniboxEventProto_ProviderInfo> ProvidersInfo;
 // Search Secondary Provider (past query in history)                   |  200*
 // Search Secondary Provider (navigational suggestion)                 |  150++
 // Search Secondary Provider (suggestion)                              |  100++
+// Non Personalized On Device Head Suggest Provider                    |   99--
 // Document Suggestions (*experimental): value controlled by Finch     |    *
 //
 // URL input type:
@@ -102,6 +103,7 @@ typedef std::vector<metrics::OmniboxEventProto_ProviderInfo> ProvidersInfo;
 // Search Secondary Provider (past query in history)                   |  200*
 // Search Secondary Provider (navigational suggestion)                 |  150++
 // Search Secondary Provider (suggestion)                              |  100++
+// Non Personalized On Device Head Suggest Provider                    |   99--
 //
 // (A search keyword is a keyword with a replacement string; a bookmark keyword
 // is a keyword with no replacement string, that is, a shortcut for a URL.)
@@ -142,6 +144,7 @@ class AutocompleteProvider
     TYPE_ZERO_SUGGEST = 1 << 7,
     TYPE_CLIPBOARD = 1 << 8,
     TYPE_DOCUMENT = 1 << 9,
+    TYPE_ON_DEVICE_HEAD = 1 << 10,
   };
 
   explicit AutocompleteProvider(Type type);

third_party/metrics_proto/README.chromium

 Name: Metrics Protos
 Short Name: metrics_proto
 URL: This is the canonical public repository
-Version: 234842562
-Date: 2019/02/20 UTC
+Version: 235268166
+Date: 2019/02/22 UTC
 License: BSD
 Security Critical: Yes
 

third_party/metrics_proto/omnibox_event.proto

@@ -197,6 +197,9 @@ message OmniboxEventProto {
     PHYSICAL_WEB = 15;  // DEPRECATED. Suggestions triggered by URLs broadcast
                         // by nearby devices.
     DOCUMENT = 16;      // Suggestions for documents in a cloud corpus.
+    // Non personalized query suggestions generated from a lightweight on device
+    // head model.
+    ON_DEVICE_HEAD = 17;
   }
 
   // The result set displayed on the completion popup