win: Add implementation of system_snapshot for Windows

snapshot/snapshot.gyp

Index: snapshot/snapshot.gyp
diff --git a/snapshot/snapshot.gyp b/snapshot/snapshot.gyp
index 894fd061f6f2552aae735e51d5c9301369d115df..0021c425b749ff191fc80cfdce68a21d3e341bec 100644
--- a/snapshot/snapshot.gyp
+++ b/snapshot/snapshot.gyp
@@ -72,7 +72,20 @@
         'process_snapshot.h',
         'system_snapshot.h',
         'thread_snapshot.h',
+        'win/process_reader_win.cc',
+        'win/process_reader_win.h',
+        'win/system_snapshot_win.cc',
+        'win/system_snapshot_win.h',
       ],
+      'conditions': [
+        ['OS=="win"', {
+          'link_settings': {
+            'libraries': [
+              '-lpowrprof.lib',
+            ],
+          },
+        }],
+      ]
     },
     {
       'target_name': 'snapshot_test_lib',
@@ -128,6 +141,7 @@
         'mac/process_reader_test.cc',
         'mac/process_types_test.cc',
         'mac/system_snapshot_mac_test.cc',
+        'win/system_snapshot_win_test.cc',
       ],
     },
   ],