logd: rework logic for LogTimeEntry

LogTimeEntry's lifecycle is spread out in various locations.  It
further seems incomplete as there is logic that assumes that its
associated thread can exit while the underlying LogTimeEntry remains
valid, however it doesn't appear that that is actually a supported
situation.

This change simplifies this logic to have only one valid state for a
LogTimeEntry: it must have its thread running and be present in
LastLogTimes.  A LogTimeEntry will never be placed into LastLogTimes
unless its thread is running and its thread will remove its associated
LogTimeEntry from LastLogTimes before it has exited.

This admittedly breaks situations where a blocking socket gets issued
multiple commands with different pid filters, tail lines, etc,
however, I'm reasonably sure that these situations were already
broken.  A check is added to close the socket in this case.

Test: multiple logcat instances work, logd.reader.per's are cleaned up
Change-Id: Ibe8651e7d530c5e9a8d6ce3150cd247982887cbe
diff --git a/logd/FlushCommand.h b/logd/FlushCommand.h
index 543dfc3..ceaf393 100644
--- a/logd/FlushCommand.h
+++ b/logd/FlushCommand.h
@@ -27,36 +27,11 @@
 
 class FlushCommand : public SocketClientCommand {
     LogReader& mReader;
-    bool mNonBlock;
-    unsigned long mTail;
     log_mask_t mLogMask;
-    pid_t mPid;
-    log_time mStart;
-    uint64_t mTimeout;
 
    public:
-    // for opening a reader
-    explicit FlushCommand(LogReader& reader, bool nonBlock, unsigned long tail,
-                          log_mask_t logMask, pid_t pid, log_time start,
-                          uint64_t timeout)
-        : mReader(reader),
-          mNonBlock(nonBlock),
-          mTail(tail),
-          mLogMask(logMask),
-          mPid(pid),
-          mStart(start),
-          mTimeout((start != log_time::EPOCH) ? timeout : 0) {
-    }
-
-    // for notification of an update
     explicit FlushCommand(LogReader& reader, log_mask_t logMask)
-        : mReader(reader),
-          mNonBlock(false),
-          mTail(-1),
-          mLogMask(logMask),
-          mPid(0),
-          mStart(log_time::EPOCH),
-          mTimeout(0) {
+        : mReader(reader), mLogMask(logMask) {
     }
 
     virtual void runSocketCommand(SocketClient* client);