Add missing test targets to the Linux ASan bots on chromium.memory.

When converting those bots to recipes in r287833, "unit" was replaced with
"unit_tests". In fact, "unit" is a composite step that includes 5 other targets
besides "unit_tests". This CL adds those targets back.

This CL also adds accessibility_unittests and gfx_unittests, which presently run
on the linux_asan trybot and on other waterfalls, but not on chromium.memory.
The same should be done to cast_unittests and google_apis_unittests, once they
are green under ASan.

BUG=none
R=glider@chromium.org
TBR=phajdan.jr@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/498443002

Cr-Commit-Position: refs/heads/master@{#291176}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@291176 0039d316-1c4b-4281-b951-d872f2087c98

testing/buildbot/chromium.memory.json

@@ -15,11 +15,18 @@
   },
   "Linux ASan LSan Tests (2)": {
     "gtest_tests": [
+      "accessibility_unittests",
+      "content_unittests",
       "display_unittests",
+      "gfx_unittests",
+      "ipc_tests",
       "media_unittests",
       "ppapi_unittests",
       "printing_unittests",
       "remoting_unittests",
+      "sql_unittests",
+      "sync_unit_tests",
+      "ui_unittests",
       "unit_tests",
       "url_unittests",
       {"test": "browser_tests", "shard_index": 1, "total_shards": 3}