Add support of <APEX>_backing.txt in mixed build.

Bug: 239081456
Test: CIs
Change-Id: I8a8a5e606d5b1bc19294fc92cd469e7aa01cdb43
diff --git a/apex/apex.go b/apex/apex.go
index ff0f504..3676607 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -1908,8 +1908,7 @@
 		// TODO(b/239081457): Generate the bazel bundle module file from the apex rule.
 		a.bundleModuleFile = android.PathForBazelOut(ctx, a.Name()+apexType.suffix()+"-base.zip")
 		a.nativeApisUsedByModuleFile = android.ModuleOutPath(android.PathForBazelOut(ctx, outputs.SymbolsUsedByApex))
-		// TODO(b/239081456): Generate the backing.txt file from Bazel.
-		a.nativeApisBackedByModuleFile = android.ModuleOutPath(android.PathForBazelOut(ctx, a.Name()+"_backing.txt"))
+		a.nativeApisBackedByModuleFile = android.ModuleOutPath(android.PathForBazelOut(ctx, outputs.BackingLibs))
 		// TODO(b/239084755): Generate the java api using.xml file from Bazel.
 		a.javaApisUsedByModuleFile = android.ModuleOutPath(android.PathForBazelOut(ctx, a.Name()+"_using.xml"))
 		installSuffix := imageApexSuffix
diff --git a/bazel/cquery/request_type.go b/bazel/cquery/request_type.go
index 572bbd1..e47e85f 100644
--- a/bazel/cquery/request_type.go
+++ b/bazel/cquery/request_type.go
@@ -219,6 +219,7 @@
     "container_key_info": [container_key_info.pem.path, container_key_info.pk8.path, container_key_info.key_name],
     "package_name": info.package_name,
     "symbols_used_by_apex": info.symbols_used_by_apex.path,
+    "backing_libs": info.backing_libs.path,
 })`
 }
 
@@ -231,6 +232,7 @@
 	ContainerKeyInfo  []string `json:"container_key_info"`
 	PackageName       string   `json:"package_name"`
 	SymbolsUsedByApex string   `json:"symbols_used_by_apex"`
+	BackingLibs       string   `json:"backing_libs"`
 }
 
 // ParseResult returns a value obtained by parsing the result of the request's Starlark function.
diff --git a/bazel/cquery/request_type_test.go b/bazel/cquery/request_type_test.go
index c7eb84e..2c35489 100644
--- a/bazel/cquery/request_type_test.go
+++ b/bazel/cquery/request_type_test.go
@@ -149,6 +149,7 @@
 				`"container_key_info":["foo.x509.pem", "foo.pk8", "foo"],` +
 				`"package_name":"package.name",` +
 				`"symbols_used_by_apex": "path/to/my.apex_using.txt",` +
+				`"backing_libs":"path/to/backing.txt",` +
 				`"provides_native_libs":[]}`,
 			expectedOutput: ApexInfo{
 				SignedOutput:      "my.apex",
@@ -159,6 +160,7 @@
 				ContainerKeyInfo:  []string{"foo.x509.pem", "foo.pk8", "foo"},
 				PackageName:       "package.name",
 				SymbolsUsedByApex: "path/to/my.apex_using.txt",
+				BackingLibs:       "path/to/backing.txt",
 			},
 		},
 	}