Drop Precise blink builders on chromium.webkit, add corresponding Trusty builders.

scripts/slave/recipes/chromium.expected/chromium_webkit_warnings.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_MODULE[depot_tools::bot_update]/resources/bot_update.py",
       "--spec",
       "cache_dir = '[GIT_CACHE]'\nsolutions = [{'deps_file': '.DEPS.git', 'managed': True, 'name': 'src', 'url': 'https://chromium.googlesource.com/chromium/src.git'}]",
       "--patch_root",
       "src",
@@ skipping 179 matching lines @@
       "-u",
       "[SLAVE_BUILD]/src/testing/scripts/get_compile_targets.py",
       "--output",
       "/path/to/tmp/json",
       "--",
       "--build-config-fs",
       "Release",
       "--paths",
       "{\"checkout\": \"[SLAVE_BUILD]/src\", \"runit.py\": \"RECIPE_PACKAGE_REPO[build]/scripts/tools/runit.py\", \"runtest.py\": \"RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py\"}",
       "--properties",
-      "{\"buildername\": \"WebKit Linux Precise\", \"buildnumber\": 571, \"mastername\": \"chromium.webkit\", \"slavename\": \"TestSlavename\", \"target_platform\": \"linux\"}"
+      "{\"buildername\": \"WebKit Linux Trusty\", \"buildnumber\": 571, \"mastername\": \"chromium.webkit\", \"slavename\": \"TestSlavename\", \"target_platform\": \"linux\"}"
     ],
     "name": "get compile targets for scripts",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@{}@@@",
       "@@@STEP_LOG_END@json.output@@@"
     ]
   },
   {
     "cmd": [
       "python",
@@ skipping 22 matching lines @@
   },
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/src/tools/mb/mb.py",
       "gen",
       "-m",
       "chromium.webkit",
       "-b",
-      "WebKit Linux Precise",
+      "WebKit Linux Trusty",
       "--config-file",
       "[SLAVE_BUILD]/src/tools/mb/mb_config.pyl",
       "--goma-dir",
       "[CACHE]/cipd/goma",
       "//out/Release"
     ],
     "cwd": "[SLAVE_BUILD]/src",
     "env": {
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
     },
@@ skipping 11 matching lines @@
       "RECIPE_PACKAGE_REPO[depot_tools]/gsutil.py",
       "--ninja-path",
       "RECIPE_PACKAGE_REPO[depot_tools]/ninja",
       "--target",
       "Release",
       "--src-dir",
       "[SLAVE_BUILD]/src",
       "--goma-cache-dir",
       "[GOMA_CACHE]",
       "--buildbot-buildername",
-      "WebKit Linux Precise",
+      "WebKit Linux Trusty",
       "--buildbot-mastername",
       "chromium.webkit",
       "--buildbot-slavename",
       "TestSlavename",
       "--goma-deps-cache-file",
-      "WebKit_Linux_Precise.gomadeps",
+      "WebKit_Linux_Trusty.gomadeps",
       "--compiler",
       "goma",
       "--goma-jsonstatus",
       "/path/to/tmp/json",
       "--goma-service-account-json-file",
       "/creds/service_accounts/service-account-goma-client.json",
       "--goma-dir",
       "[CACHE]/cipd/goma",
       "--ninja-ensure-up-to-date",
       "--",
@@ skipping 10 matching lines @@
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/runtest.py",
       "--target",
       "Release",
       "--no-xvfb",
       "--factory-properties",
-      "{\"blamelist\": [\"cool_dev1337@chromium.org\", \"hax@chromium.org\"], \"buildername\": \"WebKit Linux Precise\", \"buildnumber\": 571, \"mastername\": \"chromium.webkit\", \"recipe\": \"chromium\", \"slavename\": \"TestSlavename\", \"workdir\": \"/path/to/workdir/TestSlavename\"}",
+      "{\"blamelist\": [\"cool_dev1337@chromium.org\", \"hax@chromium.org\"], \"buildername\": \"WebKit Linux Trusty\", \"buildnumber\": 571, \"mastername\": \"chromium.webkit\", \"recipe\": \"chromium\", \"slavename\": \"TestSlavename\", \"workdir\": \"/path/to/workdir/TestSlavename\"}",
       "--build-properties",
-      "{\"blamelist\": [\"cool_dev1337@chromium.org\", \"hax@chromium.org\"], \"buildername\": \"WebKit Linux Precise\", \"buildnumber\": 571, \"mastername\": \"chromium.webkit\", \"recipe\": \"chromium\", \"slavename\": \"TestSlavename\", \"workdir\": \"/path/to/workdir/TestSlavename\"}",
+      "{\"blamelist\": [\"cool_dev1337@chromium.org\", \"hax@chromium.org\"], \"buildername\": \"WebKit Linux Trusty\", \"buildnumber\": 571, \"mastername\": \"chromium.webkit\", \"recipe\": \"chromium\", \"slavename\": \"TestSlavename\", \"workdir\": \"/path/to/workdir/TestSlavename\"}",
       "--step-name=webkit_tests",
-      "--builder-name=WebKit Linux Precise",
+      "--builder-name=WebKit Linux Trusty",
       "--slave-name=TestSlavename",
       "--build-number=571",
       "--run-python-script",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/chromium/layout_test_wrapper.py",
       "--target",
       "Release",
       "-o",
       "[SLAVE_BUILD]/layout-test-results",
       "--build-dir",
       "[SLAVE_BUILD]/src/out",
       "--json-test-results",
       "/path/to/tmp/json",
       "--test-results-server",
       "test-results.appspot.com",
       "--build-number",
       "571",
       "--builder-name",
-      "WebKit Linux Precise",
+      "WebKit Linux Trusty",
       "--step-name",
       "webkit_tests"
     ],
     "env": {
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
     },
     "name": "webkit_tests",
     "~followup_annotations": [
       "@@@STEP_TEXT@<br/>unexpected_flakes:<br/>flake/flakey.html<br/><br/>Total executed: 9001<br/>@@@",
       "@@@STEP_WARNINGS@@@"
     ]
   },
   {
     "cmd": [
       "python",
       "-u",
       "RECIPE_PACKAGE_REPO[build]/scripts/slave/chromium/archive_layout_test_results.py",
       "--results-dir",
       "[SLAVE_BUILD]/layout-test-results",
       "--build-dir",
       "[SLAVE_BUILD]/src/out",
       "--build-number",
       "571",
       "--builder-name",
-      "WebKit Linux Precise",
+      "WebKit Linux Trusty",
       "--gs-bucket",
       "gs://chromium-layout-test-archives",
       "--staging-dir",
       "[CACHE]/chrome_staging"
     ],
     "env": {
       "GOMA_SERVICE_ACCOUNT_JSON_FILE": "/creds/service_accounts/service-account-goma-client.json"
     },
     "name": "archive_webkit_tests_results",
     "~followup_annotations": [
-      "@@@STEP_LINK@layout_test_results@https://storage.googleapis.com/chromium-layout-test-archives/WebKit_Linux_Precise/571/layout-test-results/results.html@@@",
-      "@@@STEP_LINK@(zip)@https://storage.googleapis.com/chromium-layout-test-archives/WebKit_Linux_Precise/571/layout-test-results.zip@@@"
+      "@@@STEP_LINK@layout_test_results@https://storage.googleapis.com/chromium-layout-test-archives/WebKit_Linux_Trusty/571/layout-test-results/results.html@@@",
+      "@@@STEP_LINK@(zip)@https://storage.googleapis.com/chromium-layout-test-archives/WebKit_Linux_Trusty/571/layout-test-results.zip@@@"
     ]
   },
   {
     "name": "$result",
     "recipe_result": null,
     "status_code": 0
   }
 ]