Use EventHandler.Do()

Bug: N/A
Test: manually verified (e.g. ran `m nothing` successfully)
Change-Id: Ie832019f8a81e127e64946070a712126997f7a35
diff --git a/cmd/soong_build/main.go b/cmd/soong_build/main.go
index a51db36..b1e119f 100644
--- a/cmd/soong_build/main.go
+++ b/cmd/soong_build/main.go
@@ -475,88 +475,88 @@
 // Bazel BUILD files instead of Ninja files.
 func runBp2Build(configuration android.Config, extraNinjaDeps []string) {
 	eventHandler := metrics.EventHandler{}
-	eventHandler.Begin("bp2build")
+	var metrics bp2build.CodegenMetrics
+	eventHandler.Do("bp2build", func() {
 
-	// Register an alternate set of singletons and mutators for bazel
-	// conversion for Bazel conversion.
-	bp2buildCtx := android.NewContext(configuration)
+		// Register an alternate set of singletons and mutators for bazel
+		// conversion for Bazel conversion.
+		bp2buildCtx := android.NewContext(configuration)
 
-	// Soong internals like LoadHooks behave differently when running as
-	// bp2build. This is the bit to differentiate between Soong-as-Soong and
-	// Soong-as-bp2build.
-	bp2buildCtx.SetRunningAsBp2build()
+		// Soong internals like LoadHooks behave differently when running as
+		// bp2build. This is the bit to differentiate between Soong-as-Soong and
+		// Soong-as-bp2build.
+		bp2buildCtx.SetRunningAsBp2build()
 
-	// Propagate "allow misssing dependencies" bit. This is normally set in
-	// newContext(), but we create bp2buildCtx without calling that method.
-	bp2buildCtx.SetAllowMissingDependencies(configuration.AllowMissingDependencies())
-	bp2buildCtx.SetNameInterface(newNameResolver(configuration))
-	bp2buildCtx.RegisterForBazelConversion()
+		// Propagate "allow misssing dependencies" bit. This is normally set in
+		// newContext(), but we create bp2buildCtx without calling that method.
+		bp2buildCtx.SetAllowMissingDependencies(configuration.AllowMissingDependencies())
+		bp2buildCtx.SetNameInterface(newNameResolver(configuration))
+		bp2buildCtx.RegisterForBazelConversion()
 
-	// The bp2build process is a purely functional process that only depends on
-	// Android.bp files. It must not depend on the values of per-build product
-	// configurations or variables, since those will generate different BUILD
-	// files based on how the user has configured their tree.
-	bp2buildCtx.SetModuleListFile(cmdlineArgs.ModuleListFile)
-	modulePaths, err := bp2buildCtx.ListModulePaths(".")
-	if err != nil {
-		panic(err)
-	}
+		// The bp2build process is a purely functional process that only depends on
+		// Android.bp files. It must not depend on the values of per-build product
+		// configurations or variables, since those will generate different BUILD
+		// files based on how the user has configured their tree.
+		bp2buildCtx.SetModuleListFile(cmdlineArgs.ModuleListFile)
+		modulePaths, err := bp2buildCtx.ListModulePaths(".")
+		if err != nil {
+			panic(err)
+		}
 
-	extraNinjaDeps = append(extraNinjaDeps, modulePaths...)
+		extraNinjaDeps = append(extraNinjaDeps, modulePaths...)
 
-	// Run the loading and analysis pipeline to prepare the graph of regular
-	// Modules parsed from Android.bp files, and the BazelTargetModules mapped
-	// from the regular Modules.
-	blueprintArgs := cmdlineArgs
-	ninjaDeps := bootstrap.RunBlueprint(blueprintArgs, bootstrap.StopBeforePrepareBuildActions, bp2buildCtx.Context, configuration)
-	ninjaDeps = append(ninjaDeps, extraNinjaDeps...)
+		// Run the loading and analysis pipeline to prepare the graph of regular
+		// Modules parsed from Android.bp files, and the BazelTargetModules mapped
+		// from the regular Modules.
+		blueprintArgs := cmdlineArgs
+		ninjaDeps := bootstrap.RunBlueprint(blueprintArgs, bootstrap.StopBeforePrepareBuildActions, bp2buildCtx.Context, configuration)
+		ninjaDeps = append(ninjaDeps, extraNinjaDeps...)
 
-	globListFiles := writeBuildGlobsNinjaFile(bp2buildCtx, configuration.SoongOutDir(), configuration)
-	ninjaDeps = append(ninjaDeps, globListFiles...)
+		globListFiles := writeBuildGlobsNinjaFile(bp2buildCtx, configuration.SoongOutDir(), configuration)
+		ninjaDeps = append(ninjaDeps, globListFiles...)
 
-	// Run the code-generation phase to convert BazelTargetModules to BUILD files
-	// and print conversion metrics to the user.
-	codegenContext := bp2build.NewCodegenContext(configuration, *bp2buildCtx, bp2build.Bp2Build)
-	metrics := bp2build.Codegen(codegenContext)
+		// Run the code-generation phase to convert BazelTargetModules to BUILD files
+		// and print conversion metrics to the user.
+		codegenContext := bp2build.NewCodegenContext(configuration, *bp2buildCtx, bp2build.Bp2Build)
+		metrics = bp2build.Codegen(codegenContext)
 
-	generatedRoot := shared.JoinPath(configuration.SoongOutDir(), "bp2build")
-	workspaceRoot := shared.JoinPath(configuration.SoongOutDir(), "workspace")
+		generatedRoot := shared.JoinPath(configuration.SoongOutDir(), "bp2build")
+		workspaceRoot := shared.JoinPath(configuration.SoongOutDir(), "workspace")
 
-	excludes := []string{
-		"bazel-bin",
-		"bazel-genfiles",
-		"bazel-out",
-		"bazel-testlogs",
-		"bazel-" + filepath.Base(topDir),
-	}
+		excludes := []string{
+			"bazel-bin",
+			"bazel-genfiles",
+			"bazel-out",
+			"bazel-testlogs",
+			"bazel-" + filepath.Base(topDir),
+		}
 
-	if outDir[0] != '/' {
-		excludes = append(excludes, outDir)
-	}
+		if outDir[0] != '/' {
+			excludes = append(excludes, outDir)
+		}
 
-	existingBazelRelatedFiles, err := getExistingBazelRelatedFiles(topDir)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "Error determining existing Bazel-related files: %s\n", err)
-		os.Exit(1)
-	}
+		existingBazelRelatedFiles, err := getExistingBazelRelatedFiles(topDir)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Error determining existing Bazel-related files: %s\n", err)
+			os.Exit(1)
+		}
 
-	pathsToIgnoredBuildFiles := getPathsToIgnoredBuildFiles(topDir, generatedRoot, existingBazelRelatedFiles, configuration.IsEnvTrue("BP2BUILD_VERBOSE"))
-	excludes = append(excludes, pathsToIgnoredBuildFiles...)
+		pathsToIgnoredBuildFiles := getPathsToIgnoredBuildFiles(topDir, generatedRoot, existingBazelRelatedFiles, configuration.IsEnvTrue("BP2BUILD_VERBOSE"))
+		excludes = append(excludes, pathsToIgnoredBuildFiles...)
 
-	excludes = append(excludes, getTemporaryExcludes()...)
+		excludes = append(excludes, getTemporaryExcludes()...)
 
-	symlinkForestDeps := bp2build.PlantSymlinkForest(
-		topDir, workspaceRoot, generatedRoot, ".", excludes)
+		symlinkForestDeps := bp2build.PlantSymlinkForest(
+			topDir, workspaceRoot, generatedRoot, ".", excludes)
 
-	ninjaDeps = append(ninjaDeps, codegenContext.AdditionalNinjaDeps()...)
-	ninjaDeps = append(ninjaDeps, symlinkForestDeps...)
+		ninjaDeps = append(ninjaDeps, codegenContext.AdditionalNinjaDeps()...)
+		ninjaDeps = append(ninjaDeps, symlinkForestDeps...)
 
-	writeDepFile(bp2buildMarker, eventHandler, ninjaDeps)
+		writeDepFile(bp2buildMarker, eventHandler, ninjaDeps)
 
-	// Create an empty bp2build marker file.
-	touch(shared.JoinPath(topDir, bp2buildMarker))
-
-	eventHandler.End("bp2build")
+		// Create an empty bp2build marker file.
+		touch(shared.JoinPath(topDir, bp2buildMarker))
+	})
 
 	// Only report metrics when in bp2build mode. The metrics aren't relevant
 	// for queryview, since that's a total repo-wide conversion and there's a