Merge "Improve how we manage the previous app." into ics-mr1

services/java/com/android/server/am/ActivityManagerService.java

@@ -414,7 +414,12 @@ public final class ActivityManagerService extends ActivityManagerNative
      * is in a different process from the one they are currently in.
      */
     ProcessRecord mPreviousProcess;
-    
+
+    /**
+     * The time at which the previous process was last visible.
+     */
+    long mPreviousProcessVisibleTime;
+
     /**
      * Packages that the user has asked to have run in screen size
      * compatibility mode instead of filling the screen.
@@ -8361,6 +8366,12 @@ public final class ActivityManagerService extends ActivityManagerNative
         pw.println();
         pw.println("  mHomeProcess: " + mHomeProcess);
         pw.println("  mPreviousProcess: " + mPreviousProcess);
+        if (dumpAll) {
+            StringBuilder sb = new StringBuilder(128);
+            sb.append("  mPreviousProcessVisibleTime: ");
+            TimeUtils.formatDuration(mPreviousProcessVisibleTime, sb);
+            pw.println(sb);
+        }
         if (mHeavyWeightProcess != null) {
             pw.println("  mHeavyWeightProcess: " + mHeavyWeightProcess);
         }

services/java/com/android/server/am/ActivityRecord.java

@@ -80,6 +80,7 @@ final class ActivityRecord {
     ThumbnailHolder thumbHolder; // where our thumbnails should go.
     long launchTime;        // when we starting launching this activity
     long startTime;         // last time this activity was started
+    long lastVisibleTime;   // last time this activity became visible
     long cpuTimeAtResume;   // the cpu time of host process at the time of resuming activity
     Configuration configuration; // configuration activity was last running in
     CompatibilityInfo compat;// last used compatibility mode
@@ -188,6 +189,10 @@ final class ActivityRecord {
                     TimeUtils.formatDuration(launchTime, pw); pw.print(" startTime=");
                     TimeUtils.formatDuration(startTime, pw); pw.println("");
         }
+        if (lastVisibleTime != 0) {
+            pw.print(prefix); pw.print("lastVisibleTime=");
+                    TimeUtils.formatDuration(lastVisibleTime, pw); pw.println("");
+        }
         if (waitingVisible || nowVisible) {
             pw.print(prefix); pw.print("waitingVisible="); pw.print(waitingVisible);
                     pw.print(" nowVisible="); pw.println(nowVisible);
@@ -632,6 +637,7 @@ final class ActivityRecord {
                     ActivityManagerService.TAG, "windowsVisible(): " + this);
             if (!nowVisible) {
                 nowVisible = true;
+                lastVisibleTime = SystemClock.uptimeMillis();
                 if (!idle) {
                     // Instead of doing the full stop routine here, let's just
                     // hide any activities we now can, and let them stop when

services/java/com/android/server/am/ActivityStack.java

@@ -949,6 +949,22 @@ final class ActivityStack {
             if (r.configDestroy) {
                 destroyActivityLocked(r, true, false, "stop-config");
                 resumeTopActivityLocked(null);
+            } else {
+                // Now that this process has stopped, we may want to consider
+                // it to be the previous app to try to keep around in case
+                // the user wants to return to it.
+                ProcessRecord fgApp = null;
+                if (mResumedActivity != null) {
+                    fgApp = mResumedActivity.app;
+                } else if (mPausingActivity != null) {
+                    fgApp = mPausingActivity.app;
+                }
+                if (r.app != null && fgApp != null && r.app != fgApp
+                        && r.lastVisibleTime > mService.mPreviousProcessVisibleTime
+                        && r.app != mService.mHomeProcess) {
+                    mService.mPreviousProcess = r.app;
+                    mService.mPreviousProcessVisibleTime = r.lastVisibleTime;
+                }
             }
         }
     }
@@ -1363,14 +1379,6 @@ final class ActivityStack {
                         + ", nowVisible=" + next.nowVisible);
                 }
             }
-
-            if (!prev.finishing && prev.app != null && prev.app != next.app
-                    && prev.app != mService.mHomeProcess) {
-                // We are switching to a new activity that is in a different
-                // process than the previous one.  Note the previous process,
-                // so we can try to keep it around.
-                mService.mPreviousProcess = prev.app;
-            }
         }
 
         // Launching this app's activity, make sure the app is no longer