Some bots should only run on the master branch

Bug: skia:6556
Change-Id: Iebe8b30de70685f56b795521ccc2242b0682000b
Reviewed-on: https://skia-review.googlesource.com/28660
Reviewed-by: Ben Wagner <benjaminwagner@google.com>
Commit-Queue: Eric Boren <borenet@google.com>
diff --git a/infra/bots/gen_tasks.go b/infra/bots/gen_tasks.go
index 7d03526..f19bb56 100644
--- a/infra/bots/gen_tasks.go
+++ b/infra/bots/gen_tasks.go
@@ -947,18 +947,14 @@
 	j := &specs.JobSpec{
 		Priority:  0.8,
 		TaskSpecs: deps,
+		Trigger:   specs.TRIGGER_ANY_BRANCH,
 	}
-	if name == "Housekeeper-Nightly-RecreateSKPs_Canary" {
-		j.Trigger = "nightly"
-	}
-	if name == "Housekeeper-Nightly-UpdateMetaConfig" {
-		j.Trigger = "nightly"
-	}
-	if name == "Housekeeper-Weekly-RecreateSKPs" {
-		j.Trigger = "weekly"
-	}
-	if name == "Test-Ubuntu14-GCC-GCE-CPU-AVX2-x86_64-Debug-CT_DM_1m_SKPs" {
-		j.Trigger = "weekly"
+	if strings.Contains(name, "-Nightly-") {
+		j.Trigger = specs.TRIGGER_NIGHTLY
+	} else if strings.Contains(name, "-Weekly-") || name == "Test-Ubuntu14-GCC-GCE-CPU-AVX2-x86_64-Debug-CT_DM_1m_SKPs" {
+		j.Trigger = specs.TRIGGER_WEEKLY
+	} else if strings.Contains(name, "Flutter") || strings.Contains(name, "PDFium") || strings.Contains(name, "CommandBuffer") {
+		j.Trigger = specs.TRIGGER_MASTER_ONLY
 	}
 	b.MustAddJob(name, j)
 }
diff --git a/infra/bots/tasks.json b/infra/bots/tasks.json
index 0f64553..11cdea5 100644
--- a/infra/bots/tasks.json
+++ b/infra/bots/tasks.json
@@ -250,7 +250,8 @@
       "priority": 0.8,
       "tasks": [
         "Build-Debian9-GCC-x86_64-Release-Flutter_Android"
-      ]
+      ],
+      "trigger": "master"
     },
     "Build-Debian9-GCC-x86_64-Release-Mesa": {
       "priority": 0.8,
@@ -268,13 +269,15 @@
       "priority": 0.8,
       "tasks": [
         "Build-Debian9-GCC-x86_64-Release-PDFium"
-      ]
+      ],
+      "trigger": "master"
     },
     "Build-Debian9-GCC-x86_64-Release-PDFium_SkiaPaths": {
       "priority": 0.8,
       "tasks": [
         "Build-Debian9-GCC-x86_64-Release-PDFium_SkiaPaths"
-      ]
+      ],
+      "trigger": "master"
     },
     "Build-Debian9-GCC-x86_64-Release-SKNX_NO_SIMD": {
       "priority": 0.8,
@@ -334,7 +337,8 @@
       "priority": 0.8,
       "tasks": [
         "Build-Mac-Clang-x86_64-Debug-CommandBuffer"
-      ]
+      ],
+      "trigger": "master"
     },
     "Build-Mac-Clang-x86_64-Debug-Metal": {
       "priority": 0.8,
@@ -352,7 +356,8 @@
       "priority": 0.8,
       "tasks": [
         "Build-Mac-Clang-x86_64-Release-CommandBuffer"
-      ]
+      ],
+      "trigger": "master"
     },
     "Build-Win-Clang-arm64-Release-Android": {
       "priority": 0.8,
@@ -949,7 +954,8 @@
       "priority": 0.8,
       "tasks": [
         "Upload-Perf-Mac-Clang-MacMini6.2-GPU-IntelHD4000-x86_64-Release-CommandBuffer"
-      ]
+      ],
+      "trigger": "master"
     },
     "Perf-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-CT_BENCH_1k_SKPs": {
       "priority": 0.8,
@@ -1819,7 +1825,8 @@
       "priority": 0.8,
       "tasks": [
         "Upload-Test-Mac-Clang-MacMini6.2-GPU-IntelHD4000-x86_64-Debug-CommandBuffer"
-      ]
+      ],
+      "trigger": "master"
     },
     "Test-Mac-Clang-MacMini6.2-GPU-IntelHD4000-x86_64-Release": {
       "priority": 0.8,