Send the list of used and unused resources for precache

components/precache/core/proto/precache.proto

Index: components/precache/core/proto/precache.proto
diff --git a/components/precache/core/proto/precache.proto b/components/precache/core/proto/precache.proto
index 9bdd7af9b5cf1e9d8afef82f1a4c157328d5e089..7717fcc58cb937592e1f9b145e3afadd6f25c552 100644
--- a/components/precache/core/proto/precache.proto
+++ b/components/precache/core/proto/precache.proto
@@ -4,6 +4,8 @@
 
 syntax = "proto2";
 
+import "timestamp.proto";
+
 package precache;
 
 // Chrome requires this.
@@ -13,8 +15,16 @@ option optimize_for = LITE_RUNTIME;
 message PrecacheResource {
   // The URL of the resource. This field must always be present.
   optional string url = 1;
+
+  // The tophost this resource corresponds to.
+  optional string top_host_name = 2;
 };
 
+message PrecacheManifestId {
+  // Time at the creation of this manifest.
+  optional Timestamp timestamp = 1;
+}
+
 // A manifest of cacheable resources to be precached for a specific host.
 message PrecacheManifest {
   // List of resources that we predict that the user will need if they are
@@ -23,6 +33,9 @@ message PrecacheManifest {
 
   // Experiments running on this manifest.
   optional PrecacheExperiments experiments = 2;
+
+  // Identifier for the manifest sent by the server.
+  optional PrecacheManifestId id = 3;
 };
 
 message PrecacheExperiments {