Fix a bug where cache was double-counted.

Cache was being counted as cache and also as data in the app info page.
This is due to a faulty assumption I made that getDataBytes() and
getCacheBytes() measured distinct areas of storage (in actuality,
getCacheBytes() is a subset of getDataBytes()). This improper assumption
also led to the unit test being incorrect.

Change-Id: I4144d50800f82feaecb7a0a8dff26be3e4f14da8
Fixes: 62182151
Test: Settings robotest & manual

src/com/android/settings/applications/AppStorageSettings.java

@@ -543,8 +543,8 @@ public class AppStorageSettings extends AppInfoWithHeader
             mClearCacheButton.setEnabled(false);
         } else {
             long codeSize = result.getCodeBytes();
-            long dataSize = result.getDataBytes();
             long cacheSize = result.getCacheBytes();
+            long dataSize = result.getDataBytes() - cacheSize;
 
             if (dataSize <= 0 || !mCanClearData || mDataCleared) {
                 mClearDataButton.setEnabled(false);