[Sensors MH2] Keep track of most events seen on pending queue

Bug: 148243746
Test: Load onto device and run
'adb shell lshal debug android.hardware.sensors@2.0::ISensors/default'
to observe correct output

Change-Id: I8f7d87e86860bbca229051fec35b7048c4b3268b
diff --git a/sensors/2.0/multihal/HalProxy.cpp b/sensors/2.0/multihal/HalProxy.cpp
index 7c52661..ac6f17a 100644
--- a/sensors/2.0/multihal/HalProxy.cpp
+++ b/sensors/2.0/multihal/HalProxy.cpp
@@ -290,6 +290,8 @@
     stream << "  Wakelock ref count: " << mWakelockRefCount << std::endl;
     stream << "  # of events on pending write writes queue: " << mSizePendingWriteEventsQueue
            << std::endl;
+    stream << " Most events seen on pending write events queue: "
+           << mMostEventsObservedPendingWriteEventsQueue << std::endl;
     if (!mPendingWriteEventsQueue.empty()) {
         stream << "  Size of events list on front of pending writes queue: "
                << mPendingWriteEventsQueue.front().first.size() << std::endl;
@@ -571,6 +573,8 @@
         std::vector<Event> eventsLeft(events.begin() + numToWrite, events.end());
         mPendingWriteEventsQueue.push({eventsLeft, numWakeupEvents});
         mSizePendingWriteEventsQueue += numLeft;
+        mMostEventsObservedPendingWriteEventsQueue =
+                std::max(mMostEventsObservedPendingWriteEventsQueue, mSizePendingWriteEventsQueue);
         mEventQueueWriteCV.notify_one();
     }
 }
diff --git a/sensors/2.0/multihal/include/HalProxy.h b/sensors/2.0/multihal/include/HalProxy.h
index ce28e67..978f7cf 100644
--- a/sensors/2.0/multihal/include/HalProxy.h
+++ b/sensors/2.0/multihal/include/HalProxy.h
@@ -200,6 +200,9 @@
      */
     std::queue<std::pair<std::vector<Event>, size_t>> mPendingWriteEventsQueue;
 
+    //! The most events observed on the pending write events queue for debug purposes.
+    size_t mMostEventsObservedPendingWriteEventsQueue = 0;
+
     //! The max number of events allowed in the pending write events queue
     static constexpr size_t kMaxSizePendingWriteEventsQueue = 100000;