Add reasonable defaults to RBE configuration parameters.

Test: simple one action build
Change-Id: Ic66ad2b89866a67008950035bc3b559dae4e3a3e

ui/build/rbe_test.go

@@ -83,24 +83,13 @@ func TestDumpRBEMetrics(t *testing.T) {
 func TestDumpRBEMetricsErrors(t *testing.T) {
 	ctx := testContext()
 	tests := []struct {
-		description         string
-		rbeOutputDirDefined bool
-		bootstrapProgram    string
-		expectedErr         string
+		description      string
+		bootstrapProgram string
+		expectedErr      string
 	}{{
-		description:      "output_dir not defined",
-		bootstrapProgram: rbeBootstrapProgram,
-		expectedErr:      "RBE output dir variable not defined",
-	}, {
-		description:         "stopRBE failed",
-		rbeOutputDirDefined: true,
-		bootstrapProgram:    "#!/bin/bash\nexit 1\n",
-		expectedErr:         "shutdown failed",
-	}, {
-		description:         "failed to copy metrics file",
-		rbeOutputDirDefined: true,
-		bootstrapProgram:    "#!/bin/bash\n",
-		expectedErr:         "failed to copy",
+		description:      "stopRBE failed",
+		bootstrapProgram: "#!/bin/bash\nexit 1\n",
+		expectedErr:      "shutdown failed",
 	}}
 
 	for _, tt := range tests {
@@ -124,10 +113,6 @@ func TestDumpRBEMetricsErrors(t *testing.T) {
 			env.Set("OUT_DIR", tmpDir)
 			env.Set("RBE_DIR", tmpDir)
 
-			if tt.rbeOutputDirDefined {
-				env.Set("RBE_output_dir", t.TempDir())
-			}
-
 			config := Config{&configImpl{
 				environ: env,
 			}}