Cache Backend Proxy to intercept all cache events from the IO thread.

net/net.gyp

 # Copyright 2013 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.
 
 {
   'variables': {
     'chromium_code': 1,
 
     'linux_link_kerberos%': 0,
+    'use_tracing_cache_backend%': 0,
     'conditions': [
       ['chromeos==1 or OS=="android" or OS=="ios"', {
         # Disable Kerberos on ChromeOS, Android and iOS, at least for now.
         # It needs configuration (krb5.conf and so on).
         'use_kerberos%': 0,
       }, {  # chromeos == 0
         'use_kerberos%': 1,
       }],
       ['OS=="android" and target_arch != "ia32"', {
         # The way the cache uses mmap() is inefficient on some Android devices.
@@ skipping 346 matching lines @@
         'disk_cache/sparse_control.h',
         'disk_cache/stats.cc',
         'disk_cache/stats.h',
         'disk_cache/stats_histogram.cc',
         'disk_cache/stats_histogram.h',
         'disk_cache/storage_block-inl.h',
         'disk_cache/storage_block.h',
         'disk_cache/stress_support.h',
         'disk_cache/trace.cc',
         'disk_cache/trace.h',
+        'disk_cache/tracing_cache_backend.cc',
+        'disk_cache/tracing_cache_backend.h',
         'disk_cache/simple/simple_backend_impl.cc',
         'disk_cache/simple/simple_backend_impl.h',
         'disk_cache/simple/simple_disk_format.cc',
         'disk_cache/simple/simple_disk_format.h',
         'disk_cache/simple/simple_entry_impl.cc',
         'disk_cache/simple/simple_entry_impl.h',
         'disk_cache/simple/simple_index.cc',
         'disk_cache/simple/simple_index.h',
         'disk_cache/simple/simple_synchronous_entry.cc',
         'disk_cache/simple/simple_synchronous_entry.h',
@@ skipping 718 matching lines @@
           'defines': [
             'ENABLE_BUILT_IN_DNS',
           ]
         }, { # else
           'sources!': [
             'dns/address_sorter_posix.cc',
             'dns/address_sorter_posix.h',
             'dns/dns_client.cc',
           ],
         }],
+        ['use_tracing_cache_backend==1', {
+          'defines': [
+            'USE_TRACING_CACHE_BACKEND'
+          ],
+         }],
         ['use_openssl==1', {
             'sources!': [
               'base/crypto_module_nss.cc',
               'base/keygen_handler_nss.cc',
               'base/nss_memio.c',
               'base/nss_memio.h',
               'cert/cert_database_nss.cc',
               'cert/cert_verify_proc_nss.cc',
               'cert/cert_verify_proc_nss.h',
               'cert/nss_cert_database.cc',
@@ skipping 1659 matching lines @@
                 '--result', '<@(_outputs)',
                 '--isolate', 'net_unittests.isolate',
               ],
             },
           ],
         },
       ],
     }],
   ],
 }