logd: per UID less aggressive 12.5% threshold

Per-UID quota has a threshold of 12.5% of the total log size.
If less than that space is taken by the UID, then we
will not engage the pruning based on worst UID.

Change-Id: I9f15c9a26938f1115eb75e9c28ddb073e7680e06
diff --git a/logd/LogBuffer.cpp b/logd/LogBuffer.cpp
index 1859461..d0f0a89 100644
--- a/logd/LogBuffer.cpp
+++ b/logd/LogBuffer.cpp
@@ -349,9 +349,16 @@
 
             if (sorted.get()) {
                 if (sorted[0] && sorted[1]) {
-                    worst = sorted[0]->getKey();
                     worst_sizes = sorted[0]->getSizes();
-                    second_worst_sizes = sorted[1]->getSizes();
+                    // Calculate threshold as 12.5% of available storage
+                    size_t threshold = log_buffer_size(id) / 8;
+                    if (worst_sizes > threshold) {
+                        worst = sorted[0]->getKey();
+                        second_worst_sizes = sorted[1]->getSizes();
+                        if (second_worst_sizes < threshold) {
+                            second_worst_sizes = threshold;
+                        }
+                    }
                 }
             }
         }