Add extensions_unittests suite to more Win bots.

testing/buildbot/chromium.win.json

Index: testing/buildbot/chromium.win.json
diff --git a/testing/buildbot/chromium.win.json b/testing/buildbot/chromium.win.json
index 835e89e18bd9947194709c807dc64a39397a8d51..752413ce6cc7e8126b48d8985bd3ec3ffec66892 100644
--- a/testing/buildbot/chromium.win.json
+++ b/testing/buildbot/chromium.win.json
@@ -43,6 +43,7 @@
     "gtest_tests": [
       "chrome_elf_unittests",
       "components_unittests",
+      "extensions_unittests",
       "gcm_unit_tests",
       "google_apis_unittests",
       "ipc_tests",
@@ -100,6 +101,7 @@
     "gtest_tests": [
       "chrome_elf_unittests",
       "components_unittests",
+      "extensions_unittests",
       "gcm_unit_tests",
       "google_apis_unittests",
       "ipc_tests",
@@ -166,6 +168,7 @@
     "gtest_tests": [
       "chrome_elf_unittests",
       "components_unittests",
+      "extensions_unittests",
       "gcm_unit_tests",
       "google_apis_unittests",
       "ipc_tests",
@@ -228,6 +231,7 @@
       "components_unittests",
       "gfx_unittests",
       "content_unittests",
+      "extensions_unittests",
       "ui_unittests",
       "views_unittests",
       "wm_unittests",
@@ -258,6 +262,7 @@
       "components_unittests",
       "courgette_unittests",
       "crypto_unittests",
+      "extensions_unittests",
       "gcm_unit_tests",
       "gpu_unittests",
       "url_unittests",