Metrics provider for statistical stack profiler

components/metrics/proto/call_stack_profile.proto

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Call stack sample data for a given profiling session.
+
+syntax = "proto2";
+
+option optimize_for = LITE_RUNTIME;
+
+package metrics;
+
+// Next tag: 5
+message CallStackProfile {
+
+  message Sample {
+    // The callstack. Sample.entries[0] represents the call on the top of the
+    // stack.
+    repeated CallStackEntry entries = 1;

[Ilya Sherman, 2015/03/10 01:44:46]

I'm pretty sure that the protobuf convention is to name repeated fields as
singular, i.e. "entry" rather than "entries".  This makes things like
"add_entry()" look sensible, whereas "add_entries()" looks odd.

[Mike Wittman, 2015/03/16 23:55:15]

Done.

+    // Number of times this stack signature occurs.
+    optional int64 count = 2;
+  }
+
+  // The callstack and counts.
+  repeated Sample samples = 1;
+  // List of module ids found in this sample.
+  repeated ModuleIdentifier module_ids = 2;
+
+  // Duration of this profile.
+  optional int32 profile_duration_ms = 3;
+  // Time between samples.
+  optional int32 sampling_period_ms = 4;
+}
+
+// Describes an entry in the callstack.
+message CallStackEntry {
+  // Instruction pointer subtracted by module base.
+  optional uint64 address = 1;
+  // Index to the module identifier in |module_ids| of CallStackProfile.
+  optional int32 module_id_index = 2;
+}
+
+// Uniquely identifies a module.
+message ModuleIdentifier {
+  // A hash that uniquely identifies a particular program version with high
+  // probability. This is parsed from headers of the loaded module.
+  // For binaries generated by GNU tools:
+  //   Contents of the .note.gnu.build-id field.
+  // On Windows:
+  //   GUID + AGE in the debug image headers of a module.
+  optional bytes build_id = 1;
+  // MD5Sum Prefix of the module name. This is the same hashing scheme as used
+  // to hash UMA histogram names.
+  optional fixed64 name_md5_prefix = 2;
+}

[Ilya Sherman, 2015/03/10 01:44:46]

Has this protocol buffer already been reviewed and landed in google3?  That is a
prerequisite for checking it in to the Chromium repository.  I can initially
review it here, if you prefer, but keep in mind that the google3 CL absolutely
needs to be reviewed by the internal logging and privacy teams prior to landing
this Chromium CL.

[Mike Wittman, 2015/03/16 23:55:15]

Yes, and re-reviewed with suggested changes.