Don't store arbitrary Context in singletons, which causes memory leak.

We have singletons that store a Context passed to getInstance().
The problem is that when we call them, we casually pass any Context at hand.
If it's an activity (which is often the case), it'll never be GCed.

This CL make them store the application context insteaed.

Change-Id: I1abcc2c08d3f8201416d6c14720f041693823b4e

src/com/android/email/Controller.java

@@ -71,7 +71,7 @@ public class Controller {
     private static int MESSAGEID_TO_MAILBOXID_COLUMN_MAILBOXID = 1;
 
     protected Controller(Context _context) {
-        mContext = _context;
+        mContext = _context.getApplicationContext();
         mProviderContext = _context;
         mLegacyController = MessagingController.getInstance(mContext);
         mLegacyController.addListener(mLegacyListener);
@@ -79,7 +79,6 @@ public class Controller {
 
     /**
      * Gets or creates the singleton instance of Controller.
-     * @param _context The context that will be used for all underlying system access
      */
     public synchronized static Controller getInstance(Context _context) {
         if (sInstance == null) {

src/com/android/email/MessagingController.java

@@ -124,7 +124,7 @@ public class MessagingController implements Runnable {
     private final Context mContext;
 
     protected MessagingController(Context _context) {
-        mContext = _context;
+        mContext = _context.getApplicationContext();
 
         mThread = new Thread(this);
         mThread.start();
@@ -133,8 +133,6 @@ public class MessagingController implements Runnable {
     /**
      * Gets or creates the singleton instance of MessagingController. Application is used to
      * provide a Context to classes that need it.
-     * @param application
-     * @return
      */
     public synchronized static MessagingController getInstance(Context _context) {
         if (sInstance == null) {

src/com/android/email/SecurityPolicy.java

@@ -97,7 +97,7 @@ public class SecurityPolicy {
      * Private constructor (one time only)
      */
     private SecurityPolicy(Context context) {
-        mContext = context;
+        mContext = context.getApplicationContext();
         mDPM = null;
         mAdminName = new ComponentName(context, PolicyAdmin.class);
         mAggregatePolicy = null;

src/com/android/email/mail/Sender.java

@@ -98,6 +98,7 @@ public abstract class Sender {
             throws MessagingException {
        Sender sender = sSenders.get(uri);
        if (sender == null) {
+           context = context.getApplicationContext();
            sender = findSender(context, R.xml.senders_product, uri);
            if (sender == null) {
                sender = findSender(context, R.xml.senders, uri);

src/com/android/email/mail/Store.java

@@ -167,10 +167,10 @@ public abstract class Store {
      * @throws MessagingException
      */
     public synchronized static Store getInstance(String uri, Context context,
-            PersistentDataCallbacks callbacks)
-        throws MessagingException {
+            PersistentDataCallbacks callbacks) throws MessagingException {
         Store store = sStores.get(uri);
         if (store == null) {
+            context = context.getApplicationContext();
             StoreInfo info = StoreInfo.getStoreInfo(uri, context);
             if (info != null) {
                 store = instantiateStore(info.mClassName, uri, context, callbacks);

src/com/android/email/mail/store/ExchangeStore.java

@@ -195,7 +195,7 @@ public class ExchangeStore extends Store {
          * Private constructor - use public factory.
          */
         private ExchangeTransport(URI uri, Context context) throws MessagingException {
-            mContext = context;
+            mContext = context.getApplicationContext();
             setUri(uri);
         }