Break TYPE_PC into TYPE_WIN, TYPE_MAC, TYPE_LINUX.

chrome/browser/sync/protocol/session_specifics.proto

 // Copyright (c) 2011 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.
 //
 // Sync protocol datatype extension for sessions.
 
 // Update proto_value_conversions{.h,.cc,_unittest.cc} if you change
 // any fields in this file.
 
 syntax = "proto2";
@@ skipping 12 matching lines @@
   optional SessionTab tab = 3;
 }
 // Properties of session sync objects.
 message SessionHeader {
   // Each session is composed of windows.
   repeated SessionWindow window = 2;
   // A non-unique but human-readable name to describe this client.
   optional string client_name = 3;
   // The type of device.
   enum DeviceType {
-    TYPE_PC = 1;
-    TYPE_CROS = 2;
+    TYPE_WIN = 1;
+    TYPE_MAC = 2;
+    TYPE_LINUX = 3;
+    TYPE_CROS = 4;
+    TYPE_OTHER = 5;

[ncarter (slow), 2011/08/30 21:52:30]

Why do the dangerous renumbering?

[Yaron, 2011/08/30 21:58:46]

This field was just added and has never been used anywhere. There's no code yet
that reads/writes it.

[ncarter (slow), 2011/08/30 21:59:49]

OK.

   }
   optional DeviceType device_type = 4;
 }
 message SessionWindow {
   // Unique (to the owner) id for this window.
   optional int32 window_id = 1;
   // Index of the selected tab in tabs; -1 if no tab is selected.
   optional int32 selected_tab_index = 2 [default = -1];
   // Type of the browser. Currently we only store browsers of type
   // TYPE_TABBED and TYPE_POPUP.
@@ skipping 59 matching lines @@
     CLIENT_REDIRECT = 1;
     SERVER_REDIRECT = 2;
   }
   optional PageTransition page_transition = 6 [default = TYPED];
   optional PageTransitionQualifier navigation_qualifier = 7;
 }
 
 extend EntitySpecifics {
   optional SessionSpecifics session = 50119;
 }