Record device scale factor in the metrics log

chrome/common/metrics/proto/system_profile.proto

 // Copyright (c) 2012 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;
 
 package metrics;
 
-// Next tag: 12
+// Next tag: 13
 message SystemProfileProto {
   // The time when the client was compiled/linked, in seconds since the epoch.
   optional int64 build_timestamp = 1;
 
   // A version number string for the application.
   // Most commonly this is the browser version number found in a user agent
   // string, and is typically a 4-tuple of numbers separated by periods.  In
   // cases where the user agent version might be ambiguous (example: Linux 64-
   // bit build, rather than 32-bit build, or a Windows version used in some
   // special context, such as ChromeFrame running in IE), then this may include
@@ skipping 66 matching lines @@
     // qualification reports, test device tags, etc.
     optional string hardware_class = 4;
 
     // The number of physical screens.
     optional int32 screen_count = 5;
 
     // The screen dimensions of the primary screen, in pixels.
     optional int32 primary_screen_width = 6;
     optional int32 primary_screen_height = 7;
 
+    // The device scale factor of the primary screen.
+    optional float primary_screen_scale_factor = 12;
+
     // Information on the GPU
     message Graphics {
       // The GPU manufacturer's vendor id.
       optional uint32 vendor_id = 1;
 
       // The GPU manufacturer's device id for the chip set.
       optional uint32 device_id = 2;
 
       // The driver version on the GPU.
       optional string driver_version = 3;
@@ skipping 186 matching lines @@
     // The name of the field trial, as a 32-bit identifier.
     // Currently, the identifier is a hash of the field trial's name.
     optional fixed32 name_id = 1;
 
     // The user's group within the field trial, as a 32-bit identifier.
     // Currently, the identifier is a hash of the group's name.
     optional fixed32 group_id = 2;
   }
   repeated FieldTrial field_trial = 9;
 }