Add MemoryPurgeController.ReclaimedPartitionAllocInactiveTab

third_party/WebKit/Source/platform/MemoryPurgeController.cpp

Index: third_party/WebKit/Source/platform/MemoryPurgeController.cpp
diff --git a/third_party/WebKit/Source/platform/MemoryPurgeController.cpp b/third_party/WebKit/Source/platform/MemoryPurgeController.cpp
index 2f70de222920b1ca732e20a405fa364554cb1e60..8a9f1f9e2321ab625bf93b3a304473daf2d0b1c3 100644
--- a/third_party/WebKit/Source/platform/MemoryPurgeController.cpp
+++ b/third_party/WebKit/Source/platform/MemoryPurgeController.cpp
@@ -45,7 +45,17 @@ void MemoryPurgeController::pageBecameInactive()
 
 void MemoryPurgeController::pageInactiveTask(Timer<MemoryPurgeController>*)
 {
+    static const size_t maxSizeInKB = 10 * 1024;
+
+    size_t totalSizeBefore = WTF::Partitions::totalSizeOfCommittedPages();
     purgeMemory(MemoryPurgeMode::InactiveTab);
+    size_t totalSizeAfter = WTF::Partitions::totalSizeOfCommittedPages();
+    if (totalSizeAfter >= totalSizeBefore)
+        return;
+    size_t reclaimedInKB = (totalSizeBefore - totalSizeAfter) / 1024;
+    if (reclaimedInKB >= maxSizeInKB)
+        reclaimedInKB = maxSizeInKB - 1;
+    Platform::current()->histogramEnumeration("Memory.RendererInactiveTabReclaimed", reclaimedInKB, maxSizeInKB);
 }
 
 void MemoryPurgeController::purgeMemory(MemoryPurgeMode purgeMode)