cq: run fuchsia-arm64-cast on changes to //chromecast.

Bug: 959905
Change-Id: I7847c7437709258f18b78c227811f5d3a8026582
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1639050
Commit-Queue: John Budorick <jbudorick@chromium.org>
Auto-Submit: John Budorick <jbudorick@chromium.org>
Reviewed-by: Aaron Gable <agable@chromium.org>
Cr-Commit-Position: refs/heads/master@{#667165}

docs/infra/cq_builders.md

@@ -178,6 +178,16 @@ builder.
     * [`//third_party/blink/web_tests/webgpu/.+`](https://cs.chromium.org/chromium/src/third_party/blink/web_tests/webgpu/)
     * [`//third_party/dawn/.+`](https://cs.chromium.org/chromium/src/third_party/dawn/)
 
+* [fuchsia-arm64-cast](https://ci.chromium.org/p/chromium/builders/luci.chromium.try/fuchsia-arm64-cast) ([`commit-queue.cfg` entry](https://cs.chromium.org/search/?q=package:%5Echromium$+file:commit-queue.cfg+chromium/try/fuchsia-arm64-cast)) ([matching builders](https://cs.chromium.org/search/?q=file:trybots.py+fuchsia-arm64-cast))
+
+  Path regular expressions:
+    * [`//chromecast/.+`](https://cs.chromium.org/chromium/src/chromecast/)
+
+* [fuchsia-x64-cast](https://ci.chromium.org/p/chromium/builders/luci.chromium.try/fuchsia-x64-cast) ([`commit-queue.cfg` entry](https://cs.chromium.org/search/?q=package:%5Echromium$+file:commit-queue.cfg+chromium/try/fuchsia-x64-cast)) ([matching builders](https://cs.chromium.org/search/?q=file:trybots.py+fuchsia-x64-cast))
+
+  Path regular expressions:
+    * [`//chromecast/.+`](https://cs.chromium.org/chromium/src/chromecast/)
+
 * [ios-simulator-cronet](https://ci.chromium.org/p/chromium/builders/luci.chromium.try/ios-simulator-cronet) ([`commit-queue.cfg` entry](https://cs.chromium.org/search/?q=package:%5Echromium$+file:commit-queue.cfg+chromium/try/ios-simulator-cronet)) ([matching builders](https://cs.chromium.org/search/?q=file:trybots.py+ios-simulator-cronet))
 
   Path regular expressions:

infra/config/commit-queue.cfg

@@ -237,6 +237,14 @@ config_groups {
         location_regexp: ".+/[+]/third_party/blink/web_tests/webgpu/.+"
         location_regexp: ".+/[+]/third_party/dawn/.+"
       }
+      builders {
+        name: "chromium/try/fuchsia-arm64-cast"
+        location_regexp: ".+/[+]/chromecast/.+"
+      }
+      builders {
+        name: "chromium/try/fuchsia-x64-cast"
+        location_regexp: ".+/[+]/chromecast/.+"
+      }
       builders {
         name: "chromium/try/ios-simulator-cronet"
         location_regexp: ".+/[+]/components/cronet/.+"

infra/config/cq_cfg_presubmit.py

@@ -283,7 +283,8 @@ def verify_location_regexps(regexps, verbose=True):
   invalid_regexp = False
   for regexp in regexps:
     regexp = regexp.replace('\\\\', '')
-    assert regexp.startswith(REGEX_PREFIX)
+    assert regexp.startswith(REGEX_PREFIX), (
+        'location_regexp "%s" must start with "%s"' % (regexp, REGEX_PREFIX))
     regexp = regexp[len(REGEX_PREFIX):]
     # Split by path name, so that we don't have to run os.walk on the entire
     # source tree. commit-queue.cfg always uses '/' as the path separator.

infra/config/cr-buildbucket.cfg

@@ -3710,17 +3710,37 @@ buckets {
       mixins: "linux-xenial"
       mixins: "builderless"
     }
-    builders { mixins: "linux-try" name: "fuchsia-arm64-cast" }
-    builders { mixins: "linux-try" name: "fuchsia-fyi-arm64-rel" }
-    builders { mixins: "linux-try" name: "fuchsia-fyi-x64-dbg" }
-    builders { mixins: "linux-try" name: "fuchsia-fyi-x64-rel" }
+    builders {
+      mixins: "builderless"
+      mixins: "linux-try"
+      name: "fuchsia-arm64-cast"
+    }
+    builders {
+      mixins: "builderless"
+      mixins: "linux-try"
+      name: "fuchsia-fyi-arm64-rel"
+    }
+    builders {
+      mixins: "builderless"
+      mixins: "linux-try"
+      name: "fuchsia-fyi-x64-dbg"
+    }
+    builders {
+      mixins: "builderless"
+      mixins: "linux-try"
+      name: "fuchsia-fyi-x64-rel"
+    }
     builders {
       mixins: "linux-try"
       name: "fuchsia_x64"
       mixins: "linux-xenial"
       mixins: "builderless"
     }
-    builders { mixins: "linux-try" name: "fuchsia-x64-cast" }
+    builders {
+      mixins: "builderless"
+      mixins: "linux-try"
+      name: "fuchsia-x64-cast"
+    }
     builders {
       mixins: "linux-optional-gpu-try"
       name: "gpu-fyi-try-linux-intel-dqp"