Consistent "low storage" behavior.

When freeing cached data, the caller can now provide a "reserved"
size which we won't clear cached data from.

Bug: 38008706
Test: cts-tradefed run commandAndExit cts-dev -m CtsJobSchedulerTestCases -t android.jobscheduler.cts.StorageConstraintTest
Test: cts-tradefed run commandAndExit cts-dev -m CtsAppSecurityHostTestCases -t android.appsecurity.cts.StorageHostTest
Change-Id: Ieb91b3e5345a950d4785fd7915f520f0a68a567a
diff --git a/cmds/installd/binder/android/os/IInstalld.aidl b/cmds/installd/binder/android/os/IInstalld.aidl
index 6b99c1d..6185ecb 100644
--- a/cmds/installd/binder/android/os/IInstalld.aidl
+++ b/cmds/installd/binder/android/os/IInstalld.aidl
@@ -64,7 +64,8 @@
     void removeIdmap(@utf8InCpp String overlayApkPath);
     void rmPackageDir(@utf8InCpp String packageDir);
     void markBootComplete(@utf8InCpp String instructionSet);
-    void freeCache(@nullable @utf8InCpp String uuid, long freeStorageSize, int flags);
+    void freeCache(@nullable @utf8InCpp String uuid, long targetFreeBytes,
+            long cacheReservedBytes, int flags);
     void linkNativeLibraryDirectory(@nullable @utf8InCpp String uuid,
             @utf8InCpp String packageName, @utf8InCpp String nativeLibPath32, int userId);
     void createOatDir(@utf8InCpp String oatDir, @utf8InCpp String instructionSet);