Try again to fix issue #6912004:tap on gmail notification sends me to home screen

Add a new call to the activity manager to tell it when the activity
is resumed, so it can mark its state as dirty then instead of when
it first tries to create it.

Also tweak things to update the LRU list for the upcoming activity
at the point we start pausing the current activity, to avoid an
inefficiency where we may decide to kill the process of the upcoming
activity if it is at the end of the LRU list.

Change-Id: Ia6dc8c34dc6d4b085a1efbe3a5d5f47721d55078
diff --git a/services/java/com/android/server/am/ActivityStack.java b/services/java/com/android/server/am/ActivityStack.java
index f72d318..29ee0bc 100755
--- a/services/java/com/android/server/am/ActivityStack.java
+++ b/services/java/com/android/server/am/ActivityStack.java
@@ -52,7 +52,6 @@
 import android.os.Message;
 import android.os.ParcelFileDescriptor;
 import android.os.PowerManager;
-import android.os.Process;
 import android.os.RemoteException;
 import android.os.SystemClock;
 import android.os.UserHandle;
@@ -755,8 +754,6 @@
             completeResumeLocked(r);
             checkReadyForSleepLocked();
             if (DEBUG_SAVED_STATE) Slog.i(TAG, "Launch completed; removing icicle of " + r.icicle);
-            r.icicle = null;
-            r.haveState = false;
         } else {
             // This activity is not starting in the resumed state... which
             // should look like we asked it to pause+stop (but remain visible),
@@ -1010,7 +1007,21 @@
             resumeTopActivityLocked(null);
         }
     }
-    
+
+    final void activityResumed(IBinder token) {
+        ActivityRecord r = null;
+
+        synchronized (mService) {
+            int index = indexOfTokenLocked(token);
+            if (index >= 0) {
+                r = mHistory.get(index);
+                if (DEBUG_SAVED_STATE) Slog.i(TAG, "Resumed activity; dropping state of: " + r);
+                r.icicle = null;
+                r.haveState = false;
+            }
+        }
+    }
+
     final void activityPaused(IBinder token, boolean timeout) {
         if (DEBUG_PAUSE) Slog.v(
             TAG, "Activity paused: token=" + token + ", timeout=" + timeout);
@@ -1488,6 +1499,15 @@
         // can be resumed...
         if (mResumedActivity != null) {
             if (DEBUG_SWITCH) Slog.v(TAG, "Skip resume: need to start pausing");
+            // At this point we want to put the upcoming activity's process
+            // at the top of the LRU list, since we know we will be needing it
+            // very soon and it would be a waste to let it get killed if it
+            // happens to be sitting towards the end.
+            if (next.app != null && next.app.thread != null) {
+                // No reason to do full oom adj update here; we'll let that
+                // happen whenever it needs to later.
+                mService.updateLruProcessLocked(next.app, false, true);
+            }
             startPausingLocked(userLeaving, false);
             return true;
         }
@@ -1728,11 +1748,6 @@
                         "resume-exception", true);
                 return true;
             }
-
-            // Didn't need to use the icicle, and it is now out of date.
-            if (DEBUG_SAVED_STATE) Slog.i(TAG, "Resumed activity; didn't need icicle of: " + next);
-            next.icicle = null;
-            next.haveState = false;
             next.stopped = false;
 
         } else {
@@ -2578,7 +2593,6 @@
             mDismissKeyguardOnNextActivity = false;
             mService.mWindowManager.dismissKeyguard();
         }
-        Slog.i(TAG, "DONE STARTING!");
         return err;
     }