Move classpaths.proto related info into a separate provider.

The new info struct can be easily shared with systemserverclasspath
fragments.

Bug: 180105615
Test: m nothing
Change-Id: I9986e64fdf19f4168da63c156de3dc9bcafac8d8

java/classpath_fragment.go

@@ -18,6 +18,7 @@ package java
 
 import (
 	"fmt"
+	"github.com/google/blueprint"
 	"strings"
 
 	"android/soong/android"
@@ -120,6 +121,12 @@ func (c *ClasspathFragmentBase) generateClasspathProtoBuildActions(ctx android.M
 		FlagWithOutput("--output=", c.outputFilepath)
 
 	rule.Build("classpath_fragment", "Compiling "+c.outputFilepath.String())
+
+	classpathProtoInfo := ClasspathFragmentProtoContentInfo{
+		ClasspathFragmentProtoInstallDir: c.installDirPath,
+		ClasspathFragmentProtoOutput:     c.outputFilepath,
+	}
+	ctx.SetProvider(ClasspathFragmentProtoContentInfoProvider, classpathProtoInfo)
 }
 
 func writeClasspathsJson(ctx android.ModuleContext, output android.WritablePath, jars []classpathJar) {
@@ -157,3 +164,23 @@ func (c *ClasspathFragmentBase) androidMkEntries() []android.AndroidMkEntries {
 		},
 	}}
 }
+
+var ClasspathFragmentProtoContentInfoProvider = blueprint.NewProvider(ClasspathFragmentProtoContentInfo{})
+
+type ClasspathFragmentProtoContentInfo struct {
+	// ClasspathFragmentProtoOutput is an output path for the generated classpaths.proto config of this module.
+	//
+	// The file should be copied to a relevant place on device, see ClasspathFragmentProtoInstallDir
+	// for more details.
+	ClasspathFragmentProtoOutput android.OutputPath
+
+	// ClasspathFragmentProtoInstallDir contains information about on device location for the generated classpaths.proto file.
+	//
+	// The path encodes expected sub-location within partitions, i.e. etc/classpaths/<proto-file>,
+	// for ClasspathFragmentProtoOutput. To get sub-location, instead of the full output / make path
+	// use android.InstallPath#Rel().
+	//
+	// This is only relevant for APEX modules as they perform their own installation; while regular
+	// system files are installed via ClasspathFragmentBase#androidMkEntries().
+	ClasspathFragmentProtoInstallDir android.InstallPath
+}