[iOS][infra] Build with Xcode12 on iOS clang ToT builder.

Changed Xcode version in config and OS requirement.

Bug: 1126929
Change-Id: Iece9d00be25f06df812ccfa9a82bdb4df7f85687
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2405742Reviewed-by: Garrett Beaty <gbeaty@chromium.org>
Commit-Queue: Zhaoyang Li <zhaoyangli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#806277}

infra/config/generated/cr-buildbucket.cfg

@@ -6747,7 +6747,7 @@ buckets {
       swarming_tags: "vpython:native-python-wrapper"
       dimensions: "builderless:1"
       dimensions: "cpu:x86-64"
-      dimensions: "os:Mac-10.14"
+      dimensions: "os:Mac-10.15"
       dimensions: "pool:luci.chromium.ci"
       dimensions: "ssd:1"
       exe {
@@ -6755,11 +6755,11 @@ buckets {
         cipd_version: "refs/heads/master"
         cmd: "recipes"
       }
-      properties: "{\"$build/goma\":{\"use_luci_auth\":true},\"$kitchen\":{\"devshell\":true,\"git_auth\":true},\"$recipe_engine/isolated\":{\"server\":\"https://isolateserver.appspot.com\"},\"builder_group\":\"chromium.clang\",\"perf_dashboard_machine_group\":\"ChromiumClang\",\"recipe\":\"chromium\",\"xcode_build_version\":\"11e146\"}"
+      properties: "{\"$build/goma\":{\"use_luci_auth\":true},\"$kitchen\":{\"devshell\":true,\"git_auth\":true},\"$recipe_engine/isolated\":{\"server\":\"https://isolateserver.appspot.com\"},\"builder_group\":\"chromium.clang\",\"perf_dashboard_machine_group\":\"ChromiumClang\",\"recipe\":\"chromium\",\"xcode_build_version\":\"12a8189n\"}"
       execution_timeout_secs: 43200
       caches {
-        name: "xcode_ios_11e146"
-        path: "xcode_ios_11e146.app"
+        name: "xcode_ios_12a8189n"
+        path: "xcode_ios_12a8189n.app"
       }
       build_numbers: YES
       service_account: "chromium-ci-builder@chops-service-accounts.iam.gserviceaccount.com"
@@ -6779,7 +6779,7 @@ buckets {
       swarming_tags: "vpython:native-python-wrapper"
       dimensions: "builderless:1"
       dimensions: "cpu:x86-64"
-      dimensions: "os:Mac-10.14"
+      dimensions: "os:Mac-10.15"
       dimensions: "pool:luci.chromium.ci"
       dimensions: "ssd:1"
       exe {
@@ -6787,11 +6787,11 @@ buckets {
         cipd_version: "refs/heads/master"
         cmd: "recipes"
       }
-      properties: "{\"$build/goma\":{\"use_luci_auth\":true},\"$kitchen\":{\"devshell\":true,\"git_auth\":true},\"$recipe_engine/isolated\":{\"server\":\"https://isolateserver.appspot.com\"},\"builder_group\":\"chromium.clang\",\"perf_dashboard_machine_group\":\"ChromiumClang\",\"recipe\":\"chromium\",\"xcode_build_version\":\"11e146\"}"
+      properties: "{\"$build/goma\":{\"use_luci_auth\":true},\"$kitchen\":{\"devshell\":true,\"git_auth\":true},\"$recipe_engine/isolated\":{\"server\":\"https://isolateserver.appspot.com\"},\"builder_group\":\"chromium.clang\",\"perf_dashboard_machine_group\":\"ChromiumClang\",\"recipe\":\"chromium\",\"xcode_build_version\":\"12a8189n\"}"
       execution_timeout_secs: 43200
       caches {
-        name: "xcode_ios_11e146"
-        path: "xcode_ios_11e146.app"
+        name: "xcode_ios_12a8189n"
+        path: "xcode_ios_12a8189n.app"
       }
       build_numbers: YES
       service_account: "chromium-ci-builder@chops-service-accounts.iam.gserviceaccount.com"

infra/config/subprojects/chromium/ci.star

@@ -1479,30 +1479,30 @@ ci.clang_builder(
 
 ci.clang_builder(
     name = "ToTiOS",
-    caches = [xcode_cache.x11e146],
+    caches = [xcode_cache.x12a8189n],
     console_view_entry = ci.console_view_entry(
         category = "iOS|public",
         short_name = "sim",
     ),
     cores = None,
-    os = os.MAC_10_14,
+    os = os.MAC_10_15,
     properties = {
-        "xcode_build_version": "11e146",
+        "xcode_build_version": "12a8189n",
     },
     ssd = True,
 )
 
 ci.clang_builder(
     name = "ToTiOSDevice",
-    caches = [xcode_cache.x11e146],
+    caches = [xcode_cache.x12a8189n],
     console_view_entry = ci.console_view_entry(
         category = "iOS|public",
         short_name = "dev",
     ),
     cores = None,
-    os = os.MAC_10_14,
+    os = os.MAC_10_15,
     properties = {
-        "xcode_build_version": "11e146",
+        "xcode_build_version": "12a8189n",
     },
     ssd = True,
 )