Remove env config fetcher code

This code is no longer needed since we are now setting USE_RBE to true
for 100% of users (except two users, who I'll reach out to over email).
So fetching the configuration is no longer needed since sometimes this
can result in RBE config flipping between on and off (depending on
whether you have gcert or not).

Tested: Ran the build with latest sync and ensured RBE was used for the
build.

Bug: b/283828386
Change-Id: I3cda78607b46a0e161b7841560dc587a44d91f27
diff --git a/ui/build/config.go b/ui/build/config.go
index 8ec9680..45735ad 100644
--- a/ui/build/config.go
+++ b/ui/build/config.go
@@ -15,7 +15,6 @@
 package build
 
 import (
-	"context"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
@@ -39,9 +38,6 @@
 const (
 	envConfigDir = "vendor/google/tools/soong_config"
 	jsonSuffix   = "json"
-
-	configFetcher         = "vendor/google/tools/soong/expconfigfetcher"
-	envConfigFetchTimeout = 10 * time.Second
 )
 
 var (
@@ -170,87 +166,6 @@
 	}
 }
 
-// fetchEnvConfig optionally fetches a configuration file that can then subsequently be
-// loaded into Soong environment to control certain aspects of build behavior (e.g., enabling RBE).
-// If a configuration file already exists on disk, the fetch is run in the background
-// so as to NOT block the rest of the build execution.
-func fetchEnvConfig(ctx Context, config *configImpl, envConfigName string) error {
-	configName := envConfigName + "." + jsonSuffix
-	expConfigFetcher := &smpb.ExpConfigFetcher{Filename: &configName}
-	defer func() {
-		ctx.Metrics.ExpConfigFetcher(expConfigFetcher)
-	}()
-	if !config.GoogleProdCredsExist() {
-		status := smpb.ExpConfigFetcher_MISSING_GCERT
-		expConfigFetcher.Status = &status
-		return nil
-	}
-
-	s, err := os.Stat(configFetcher)
-	if err != nil {
-		if os.IsNotExist(err) {
-			return nil
-		}
-		return err
-	}
-	if s.Mode()&0111 == 0 {
-		status := smpb.ExpConfigFetcher_ERROR
-		expConfigFetcher.Status = &status
-		return fmt.Errorf("configuration fetcher binary %v is not executable: %v", configFetcher, s.Mode())
-	}
-
-	configExists := false
-	outConfigFilePath := filepath.Join(config.OutDir(), configName)
-	if _, err := os.Stat(outConfigFilePath); err == nil {
-		configExists = true
-	}
-
-	tCtx, cancel := context.WithTimeout(ctx, envConfigFetchTimeout)
-	fetchStart := time.Now()
-	cmd := exec.CommandContext(tCtx, configFetcher, "-output_config_dir", config.OutDir(),
-		"-output_config_name", configName)
-	if err := cmd.Start(); err != nil {
-		status := smpb.ExpConfigFetcher_ERROR
-		expConfigFetcher.Status = &status
-		return err
-	}
-
-	fetchCfg := func() error {
-		if err := cmd.Wait(); err != nil {
-			status := smpb.ExpConfigFetcher_ERROR
-			expConfigFetcher.Status = &status
-			return err
-		}
-		fetchEnd := time.Now()
-		expConfigFetcher.Micros = proto.Uint64(uint64(fetchEnd.Sub(fetchStart).Microseconds()))
-		expConfigFetcher.Filename = proto.String(outConfigFilePath)
-
-		if _, err := os.Stat(outConfigFilePath); err != nil {
-			status := smpb.ExpConfigFetcher_NO_CONFIG
-			expConfigFetcher.Status = &status
-			return err
-		}
-		status := smpb.ExpConfigFetcher_CONFIG
-		expConfigFetcher.Status = &status
-		return nil
-	}
-
-	// If a config file does not exist, wait for the config file to be fetched. Otherwise
-	// fetch the config file in the background and return immediately.
-	if !configExists {
-		defer cancel()
-		return fetchCfg()
-	}
-
-	go func() {
-		defer cancel()
-		if err := fetchCfg(); err != nil {
-			ctx.Verbosef("Failed to fetch config file %v: %v\n", configName, err)
-		}
-	}()
-	return nil
-}
-
 func loadEnvConfig(ctx Context, config *configImpl, bc string) error {
 	if bc == "" {
 		return nil
@@ -350,9 +265,6 @@
 	bc := os.Getenv("ANDROID_BUILD_ENVIRONMENT_CONFIG")
 
 	if bc != "" {
-		if err := fetchEnvConfig(ctx, ret, bc); err != nil {
-			ctx.Verbosef("Failed to fetch config file: %v\n", err)
-		}
 		if err := loadEnvConfig(ctx, ret, bc); err != nil {
 			ctx.Fatalln("Failed to parse env config files: %v", err)
 		}