Make net_unittests_run work with component=shared_library.

base/base.isolate

 # 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.
 {
   'conditions': [
     ['OS=="linux" and component=="shared_library"', {
       'variables': {
         'isolate_dependency_tracked': [
           '<(PRODUCT_DIR)/lib/libbase.so',
           '<(PRODUCT_DIR)/lib/libbase_i18n.so',
-          '<(PRODUCT_DIR)/lib/libbase_prefs.so',
         ],
       },
     }],
     ['OS=="mac" and component=="shared_library"', {
       'variables': {
         'isolate_dependency_tracked': [
           '<(PRODUCT_DIR)/libbase.dylib',
           '<(PRODUCT_DIR)/libbase_i18n.dylib',
-          '<(PRODUCT_DIR)/libbase_prefs.dylib',
         ],
       },
     }],
     ['OS=="win" and component=="shared_library"', {
       'variables': {
         'isolate_dependency_tracked': [
           '<(PRODUCT_DIR)/base.dll',
           '<(PRODUCT_DIR)/base_i18n.dll',
-          '<(PRODUCT_DIR)/base_prefs.dll',
         ],
       },
     }],
   ],
+  # Important note:
+  # Running:
+  #  1. GYP_DEFINES=component=shared_library build/gyp_chromium
+  #  2. ninja -C out/Debug base
+  # will result with only libbase.so being built. Building base by itself won't
+  # force the build of icu or nss. This is because base is not usable by itself.
+  # But on the other hand any test that includes base will be building and
+  # loading at runtime both icu and nss. So define here what is brought by
+  # importing base, not what base would load at runtime.
+  #
+  # There is no such thing as direct_dependent in .isolate, so it's not the best
+  # format to describe this kind of thing. But as a user of base.so, the user
+  # will be importing these other libraries:
   'includes': [
+    # While the target 'base' doesn't depend on ../build/linux/system.gyp:ssl
+    # itself, virtually all targets using it has to include
+    # ../third_party/nss/ssl.gyp:libssl through system.gyp.
     '../build/linux/system.isolate',
+    # While the target 'base' doesn't depend on ../third_party/icu/icu.gyp
+    # itself, virtually all targets using it has to include icu. The only
+    # exception is the Windows sandbox (?).
     '../third_party/icu/icu.isolate',
   ],
 }