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..1e5ac3972e46cfe6b3bed6e27972ce8f827f2637 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 tophostname = 2;

[sclittle, 2016/08/11 22:52:36]

nit: maybe change to top_host_name?

[Raj, 2016/08/12 19:04:21]

Done.

 };
 
+message PrecacheManifestId {
+  // Time at the creation of this manifest.

[sclittle, 2016/08/11 22:52:36]

What determines this time? The server? If so, then timestamps aren't guaranteed
to be unique IDs, and this could cause weird bugs to happen.

[Raj, 2016/08/12 19:04:22]

The manifest_id(timestamp) is just an opaque data for Chrome. It need not be
unique compared to different manifests. We do not enforce uniqueness in the DB
as well.

+  optional Timestamp timestamp = 1;

[sclittle, 2016/08/11 22:52:36]

Why is this specifically a timestamp? Could this just be some opaque ID set by
the server?

[Raj, 2016/08/12 19:04:22]

I will try to change this manifest_id to a simple string or a number, so that
timestamp confusion is avoided.

+}
+
 // 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 +33,8 @@ message PrecacheManifest {
 
   // Experiments running on this manifest.
   optional PrecacheExperiments experiments = 2;
+
+  optional PrecacheManifestId id = 3;

[bengr, 2016/08/11 18:49:15]

Add a comment.

[Raj, 2016/08/12 19:04:21]

Done.

 };
 
 message PrecacheExperiments {