metrics/base: log whether drives have seek penalties.

components/metrics/proto/system_profile.proto

 // Copyright 2014 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.
 //
 // Stores information about the user's brower and system configuration.
 // The system configuration fields are recorded once per client session.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
@@ skipping 74 matching lines @@
     optional string fingerprint = 3;
 
     // Whether the version of iOS appears to be "jailbroken". This field is
     // used only on iOS. Chrome for iOS detects whether device contains a
     // DynamicLibraries/ directory. It's a necessary but insufficient indicator
     // of whether the operating system has been jailbroken.
     optional bool is_jailbroken = 4;
   }
   optional OS os = 5;
 
-  // Next tag for Hardware: 16
+  // Next tag for Hardware: 18
   // Information on the user's hardware.
   message Hardware {
     // The CPU architecture (x86, PowerPC, x86_64, ...)
     optional string cpu_architecture = 1;
 
     // The amount of RAM present on the system, in megabytes.
     optional int64 system_ram_mb = 2;
 
     // The base memory address that chrome.dll was loaded at.
     // (Logged only on Windows.)
@@ skipping 148 matching lines @@
     // Vendor ids and product ids of external touchscreens.
     message TouchScreen {
       // Touch screen vendor id.
       optional uint32 vendor_id = 1;
       // Touch screen product id.
       optional uint32 product_id = 2;
     }
     // Lists vendor and product ids of external touchscreens.
     // Logged on ChromeOS only.
     repeated TouchScreen external_touchscreen = 15;
+
+    message Drive {
+      optional bool has_seek_penalty = 1;

[Alexei Svitkine (slow), 2015/03/16 16:49:36]

This definitely needs a comment.

[Dan Beam, 2015/03/16 19:20:23]

Done.

+    }
+    // The drive that the application executable was loaded from.
+    optional Drive app_drive = 16;
+    // The drive that the current --user-data-dir was loaded from.

[Alexei Svitkine (slow), 2015/03/16 16:49:36]

Nit: I would actually just say "the user data directory" rather than mention the
command-line parameter.

[Dan Beam, 2015/03/16 19:20:23]

Done.

+    optional Drive user_data_drive = 17;
   }
   optional Hardware hardware = 6;
 
   // Information about the network connection.
   message Network {
     // Set to true if connection_type changed during the lifetime of the log.
     optional bool connection_type_is_ambiguous = 1;
 
     // See net::NetworkChangeNotifier::ConnectionType.
     enum ConnectionType {
@@ skipping 448 matching lines @@
   // then HAS_OFFSTORE is reported. This should be kept in sync with the
   // corresponding enum in chrome/browser/metrics/extensions_metrics_provider.cc
   enum ExtensionsState {
     NO_EXTENSIONS = 0;
     NO_OFFSTORE_VERIFIED = 1;
     NO_OFFSTORE_UNVERIFIED = 2;
     HAS_OFFSTORE = 3;
   }
   optional ExtensionsState offstore_extensions_state = 19;
 }