[ActivityManager] Finish the failed-to-pause activity

Symptom:
In some scenario, the mPausingActivity may be replaced by other activity.
When previous activity paused, the completePausedLocked() won't be invoked
because it is no longer the mPausingActivity. If the activity is also
pending to finish, it would never be done because the activity kept in
PAUSING state. Since the activity's window also remain visible and is
above on Wallpaper, user would see it when back to home.

Solution:
Finish the failed-to-pause activity if the activity is pending to finish

A Real Case:
(1) Screen turn off
(2) The top activity T1 crashed
(3) When finish activity T1, the next top activity T2 will be scheduled
    to resume and pause (due to screen off).
(4) The activity T2 is also set to finishing due to T1 crashed.
(5) Before T2 paused and before paused timeout occurs, there has a new
    process started which brings up the next top activity T3 to resume
    and pause. So the pausing activity is now replaced.
(6) When activity T2 paused, it cannot completed the pause operation.
    T2 will remain in PAUSING and finishing state with its window visible.
    The process won't be killed because the oomadj stays at 1 (Visible).

Change-Id: Ib10fded891b21c774b26a93071c717fa50516e22
[ActivityManager] Ensure provider external access count will be released.

Sympton: Oom-adj of provider process will be always 0.

Root Cause: Exception happend in openContentUri
may not call removeContentProviderExternalUnchecked.

Flow:
application [MediaPlayer.setDataSource(Context context, Uri uri)]
    uri is invalid, IOException will be caught and below log will appear:
    "Couldn't open file on client side, trying server side"
    Continue to call setDataSource(String path, Map<String, String> headers)
 ->mediaserver [MediaPlayerService::Client::setDataSource]
    setDataSource(httpService, url, headers) calls openContentProviderFile
 ->system_server (ActivityManagerService) [openContentUri]
    Increase externalProcessNoHandleCount for media provider.
    Call [openFile] to media provider.
 ->android.process.media [check permission for openFile]
    enforceReadPermissionInner
 ->system_server [checkComponentPermission]
    Use mediaserver's uid to check READ_EXTERNAL_STORAGE
      -> not granted due to it is pure native process, not a known package.
    Throw security exception then the flow of openContentUri is broke.
    And externalProcessNoHandleCount is unable to decrease.

Application sample code:
 String invalidId = "54321";
 Uri externalUri = MediaStore.Files.getContentUri("external");
 Uri uri = Uri.withAppendedPath(externalUri, invalidId);
 mediaPlayer.setDataSource(mContext, uri);

Solution: Move removeContentProviderExternalUnchecked to finally block.

Change-Id: I75eec1f9631e9c6bb18449946d707d51ac21e8a7
[ActivityManager] Fix NullPointerException when dumping ContentProviderRecord.

Sympton: If there is external access without handles, dumpsys will met exception as:
  * ContentProviderRecord{45ed0fc8 u0 com.android.providers.media/.MediaProvider}
...
    externals=
Exception occurred while dumping:
java.lang.NullPointerException
	at com.android.server.am.ContentProviderRecord.dump(ContentProviderRecord.java:171)

Root Cause: External handles may be empty but there is "no handle" count.

Solution: Check null and print with handle, no handle count.

Change-Id: I0ee497096113e5685d491a0d4346f57d398495e6
[ActivityManager] Fix index out of bounds when updating next pss time.

Symptom:
System server crash.

Root Cause:
The value curProcState for array index is -1 if the process has not attached yet.

Solution:
Skip compute for process which is not attached or have invalid curProcState.

Change-Id: I71aaf45bb78d73097ebe9dfebf76b72f2d243232
ContentProvider: Avoid duplicate initialization of AsyncTask

AsyncTask is being initialized by ActivityThread to ensure its static
handler initilization and ContentProvider need not duplicate the logic.

Change-Id: I48bc88bdba32b56114f09c04a75480e26508f704