bufferpool@2.0 tune eviction params

bufferpool tries to manage memory consumption as low as 15MB usually.
Since it is too harsh for graphic input buffer use cases, if # of
buffers are under certain threshold make bufferpool ignore total memory
consumption.

Bug: 141605804
Change-Id: I20bd0438fede018e26984e0e3bc9a2007b0bc29b

media/bufferpool/2.0/AccessorImpl.cpp

@@ -37,7 +37,7 @@ namespace {
     static constexpr int64_t kLogDurationUs = 5000000; // 5 secs
 
     static constexpr size_t kMinAllocBytesForEviction = 1024*1024*15;
-    static constexpr size_t kMinBufferCountForEviction = 40;
+    static constexpr size_t kMinBufferCountForEviction = 25;
 }
 
 // Buffer structure in bufferpool process
@@ -718,8 +718,8 @@ void Accessor::Impl::BufferPool::cleanUp(bool clearCache) {
                   mStats.mTotalFetches, mStats.mTotalTransfers);
         }
         for (auto freeIt = mFreeBuffers.begin(); freeIt != mFreeBuffers.end();) {
-            if (!clearCache && mStats.mSizeCached < kMinAllocBytesForEviction
+            if (!clearCache && (mStats.mSizeCached < kMinAllocBytesForEviction
-                    && mBuffers.size() < kMinBufferCountForEviction) {
+                    || mBuffers.size() < kMinBufferCountForEviction)) {
                 break;
             }
             auto it = mBuffers.find(*freeIt);