Pass --preloaded-classes to boot image compilation.

Test: m
Bug: 162110941
Change-Id: I0df016c5d170ca101cd18cacc331499ae76677a6

java/dexpreopt_bootjars.go

@@ -281,6 +281,9 @@ type bootImageConfig struct {
 
 	// Target-dependent fields.
 	variants []*bootImageVariant
+
+	// Path of the preloaded classes file.
+	preloadedClassesFile string
 }
 
 // Target-dependent description of a boot image.
@@ -680,6 +683,13 @@ func buildBootImageVariant(ctx android.ModuleContext, image *bootImageVariant, p
 		cmd.FlagWithArg("--base=", ctx.Config().LibartImgDeviceBaseAddress())
 	}
 
+	// We always expect a preloaded classes file to be available. However, if we cannot find it, it's
+	// OK to not pass the flag to dex2oat.
+	preloadedClassesPath := android.ExistentPathForSource(ctx, image.preloadedClassesFile)
+	if preloadedClassesPath.Valid() {
+		cmd.FlagWithInput("--preloaded-classes=", preloadedClassesPath.Path())
+	}
+
 	cmd.
 		FlagForEachInput("--dex-file=", image.dexPaths.Paths()).
 		FlagForEachArg("--dex-location=", image.dexLocations).

java/dexpreopt_config.go

@@ -62,6 +62,7 @@ func genBootImageConfigRaw(ctx android.PathContext) map[string]*bootImageConfig
 			installDirOnDevice:       "system/framework",
 			profileInstallPathInApex: "etc/boot-image.prof",
 			modules:                  artModules,
+			preloadedClassesFile:     "art/build/boot/preloaded-classes",
 		}
 
 		// Framework config for the boot image extension.
@@ -74,6 +75,7 @@ func genBootImageConfigRaw(ctx android.PathContext) map[string]*bootImageConfig
 			installDirOnHost:     frameworkSubdir,
 			installDirOnDevice:   frameworkSubdir,
 			modules:              frameworkModules,
+			preloadedClassesFile: "frameworks/base/config/preloaded-classes",
 		}
 
 		return map[string]*bootImageConfig{