Add R8 support

Add support for R8 to optimize apps and java libraries.

Test: m checkbuild
Change-Id: I2afd5d7a84912d3ab613c32c599bd1ebe60562e0

java/java.go

@@ -191,6 +191,32 @@ type CompilerDeviceProperties struct {
 		Profile *string
 	}
 
+	Optimize struct {
+		// If false, disable all optimization.  Defaults to true for apps, false for
+		// libraries and tests.
+		Enabled *bool
+
+		// If true, optimize for size by removing unused code.  Defaults to true for apps,
+		// false for libraries and tests.
+		Shrink *bool
+
+		// If true, optimize bytecode.  Defaults to false.
+		Optimize *bool
+
+		// If true, obfuscate bytecode.  Defaults to false.
+		Obfuscate *bool
+
+		// If true, do not use the flag files generated by aapt that automatically keep
+		// classes referenced by the app manifest.  Defaults to false.
+		No_aapt_flags *bool
+
+		// Flags to pass to proguard.
+		Proguard_flags []string
+
+		// Specifies the locations of files containing proguard flags.
+		Proguard_flags_files []string
+	}
+
 	// When targeting 1.9, override the modules to use with --system
 	System_modules *string
 }
@@ -216,6 +242,9 @@ type Module struct {
 	// output file containing uninstrumented classes that will be instrumented by jacoco
 	jacocoReportClassesFile android.Path
 
+	// output file containing mapping of obfuscated names
+	proguardDictionary android.Path
+
 	// output file suitable for installing or running
 	outputFile android.Path
 
@@ -229,6 +258,9 @@ type Module struct {
 	// list of .java files and srcjars that was passed to javac
 	compiledJavaSrcs android.Paths
 	compiledSrcJars  android.Paths
+
+	// list of extra progurad flag files
+	extraProguardFlagFiles android.Paths
 }
 
 func (j *Module) Srcs() android.Paths {
@@ -260,6 +292,7 @@ var (
 	systemModulesTag = dependencyTag{name: "system modules"}
 	frameworkResTag  = dependencyTag{name: "framework-res"}
 	kotlinStdlibTag  = dependencyTag{name: "kotlin-stdlib"}
+	proguardRaiseTag = dependencyTag{name: "proguard-raise"}
 )
 
 type sdkDep struct {
@@ -377,6 +410,10 @@ func (j *Module) deps(ctx android.BottomUpMutatorContext) {
 					ctx.AddDependency(ctx.Module(), systemModulesTag, sdkDep.systemModules)
 				}
 				ctx.AddDependency(ctx.Module(), bootClasspathTag, sdkDep.module)
+				if Bool(j.deviceProperties.Optimize.Enabled) {
+					ctx.AddDependency(ctx.Module(), proguardRaiseTag, config.DefaultBootclasspathLibraries...)
+					ctx.AddDependency(ctx.Module(), proguardRaiseTag, config.DefaultLibraries...)
+				}
 			}
 		} else if j.deviceProperties.System_modules == nil {
 			ctx.PropertyErrorf("no_standard_libs",