Implement sysprop_library API stability check

sysprop_library now checks the API stability itself, cutting dependency
on java_sdk_library. Under the directory {module_dir}/api,
{module_name}-current.txt and {module_name}-latest.txt hold API
signatures.

When sysprop_library is built, or a user run "m {module_name}-check-api"
command, API check is performed. First, current.txt must have exactly
same signature with built sysprop_library module. Second, current.txt
must be compatible with latest.txt.

Build system emits a handy error message to generate/update those API
files, in case of missing or mismatching. Also, a script file for
freezing API files is introduced.

Bug: 131637873
Test: 1) m && boot blueline
Test: 2) m {sysprop_library} performs API check
Test: 3) manual test for check-api, freezing api
Change-Id: I9d25f5dc64299e666527ca8e23d7233966901c4e
Merged-In: I9d25f5dc64299e666527ca8e23d7233966901c4e
Merged-In: Ib7ad4f17e82c90da5ef3f80e2ab88c0b53112c60
(cherry picked from commit 093f0eb1331dffaab23e9252d2a4dbc6a27156f0)
diff --git a/java/droiddoc.go b/java/droiddoc.go
index b474948..118b62c 100644
--- a/java/droiddoc.go
+++ b/java/droiddoc.go
@@ -485,9 +485,6 @@
 		case ".aidl":
 			javaFile := genAidl(ctx, srcFile, flags.aidlFlags, flags.aidlDeps)
 			outSrcFiles = append(outSrcFiles, javaFile)
-		case ".sysprop":
-			javaFile := genSysprop(ctx, srcFile)
-			outSrcFiles = append(outSrcFiles, javaFile)
 		case ".logtags":
 			javaFile := genLogtags(ctx, srcFile)
 			outSrcFiles = append(outSrcFiles, javaFile)
diff --git a/java/gen.go b/java/gen.go
index 69965ec..81fc341 100644
--- a/java/gen.go
+++ b/java/gen.go
@@ -53,13 +53,13 @@
 	sysprop = pctx.AndroidStaticRule("sysprop",
 		blueprint.RuleParams{
 			Command: `rm -rf $out.tmp && mkdir -p $out.tmp && ` +
-				`$syspropCmd --java-output-dir $out.tmp $in && ` +
+				`$syspropCmd --scope $scope --java-output-dir $out.tmp $in && ` +
 				`${config.SoongZipCmd} -jar -o $out -C $out.tmp -D $out.tmp && rm -rf $out.tmp`,
 			CommandDeps: []string{
 				"$syspropCmd",
 				"${config.SoongZipCmd}",
 			},
-		})
+		}, "scope")
 )
 
 func genAidl(ctx android.ModuleContext, aidlFile android.Path, aidlFlags string, deps android.Paths) android.Path {
@@ -98,7 +98,7 @@
 	return javaFile
 }
 
-func genSysprop(ctx android.ModuleContext, syspropFile android.Path) android.Path {
+func genSysprop(ctx android.ModuleContext, syspropFile android.Path, scope string) android.Path {
 	srcJarFile := android.GenPathWithExt(ctx, "sysprop", syspropFile, "srcjar")
 
 	ctx.Build(pctx, android.BuildParams{
@@ -106,6 +106,9 @@
 		Description: "sysprop_java " + syspropFile.Rel(),
 		Output:      srcJarFile,
 		Input:       syspropFile,
+		Args: map[string]string{
+			"scope": scope,
+		},
 	})
 
 	return srcJarFile
@@ -129,7 +132,27 @@
 			srcJarFile := genProto(ctx, srcFile, flags.proto)
 			outSrcFiles = append(outSrcFiles, srcJarFile)
 		case ".sysprop":
-			srcJarFile := genSysprop(ctx, srcFile)
+			// internal scope contains all properties
+			// public scope only contains public properties
+			// use public if the owner is different from client
+			scope := "internal"
+			if j.properties.Sysprop.Platform != nil {
+				isProduct := ctx.ProductSpecific()
+				isVendor := ctx.SocSpecific()
+				isOwnerPlatform := Bool(j.properties.Sysprop.Platform)
+
+				if isProduct {
+					// product can't own any sysprop_library now, so product must use public scope
+					scope = "public"
+				} else if isVendor && !isOwnerPlatform {
+					// vendor and odm can't use system's internal property.
+					scope = "public"
+				}
+
+				// We don't care about clients under system.
+				// They can't use sysprop_library owned by other partitions.
+			}
+			srcJarFile := genSysprop(ctx, srcFile, scope)
 			outSrcFiles = append(outSrcFiles, srcJarFile)
 		default:
 			outSrcFiles = append(outSrcFiles, srcFile)
diff --git a/java/java.go b/java/java.go
index afb1218..2193a2b 100644
--- a/java/java.go
+++ b/java/java.go
@@ -183,6 +183,10 @@
 		Output_params []string
 	}
 
+	Sysprop struct {
+		Platform *bool
+	} `blueprint:"mutated"`
+
 	Instrument bool `blueprint:"mutated"`
 
 	// List of files to include in the META-INF/services folder of the resulting jar.
@@ -1017,7 +1021,6 @@
 }
 
 func (j *Module) compile(ctx android.ModuleContext, aaptSrcJar android.Path) {
-
 	j.exportAidlIncludeDirs = android.PathsForModuleSrc(ctx, j.deviceProperties.Aidl.Export_include_dirs)
 
 	deps := j.collectDeps(ctx)