[IndexedDB] Adding txn, value, and key size metrics

content/browser/indexed_db/indexed_db_transaction.cc

Index: content/browser/indexed_db/indexed_db_transaction.cc
diff --git a/content/browser/indexed_db/indexed_db_transaction.cc b/content/browser/indexed_db/indexed_db_transaction.cc
index 904a284651a5220be85d53d13c6958292ac8756c..f5e4a5af9723a8932137848acbd1c345c799e685 100644
--- a/content/browser/indexed_db/indexed_db_transaction.cc
+++ b/content/browser/indexed_db/indexed_db_transaction.cc
@@ -8,6 +8,7 @@
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/single_thread_task_runner.h"
 #include "base/stl_util.h"
 #include "base/strings/utf_string_conversions.h"
@@ -341,6 +342,32 @@ leveldb::Status IndexedDBTransaction::CommitPhaseTwo() {
   if (!used_) {
     committed = true;
   } else {
+    const char* time_uma_name = nullptr;
+    const char* size_uma_name = nullptr;
+    switch (mode_) {
+      case blink::kWebIDBTransactionModeReadOnly:
+        time_uma_name = "WebCore.IndexedDB.Transaction.ReadOnly.TimeActive";
+        size_uma_name = "WebCore.IndexedDB.Transaction.ReadOnly.SizeOnCommit";
+        break;
+      case blink::kWebIDBTransactionModeReadWrite:
+        time_uma_name = "WebCore.IndexedDB.Transaction.ReadWrite.TimeActive";
+        size_uma_name = "WebCore.IndexedDB.Transaction.ReadWrite.SizeOnCommit";
+        break;
+      case blink::kWebIDBTransactionModeVersionChange:
+        time_uma_name =
+            "WebCore.IndexedDB.Transaction.VersionChange.TimeActive";
+        size_uma_name =
+            "WebCore.IndexedDB.Transaction.VersionChange.SizeOnCommit";
+        break;
+      default:
+        NOTREACHED();
+    }
+    UMA_HISTOGRAM_MEDIUM_TIMES(time_uma_name,

[Mark P, 2017/05/24 18:57:38]

I don't think these macros will work.  Have you tested this?  I need think you
need to use FactoryGet directly.
(time_uma_name can have different values at different times.  I think the
caching done in the macro will cause an emit to go to the wrong histogram.)

[dmurph, 2017/05/24 19:25:59]

Yep, fixed.

+                               base::Time::Now() - diagnostics_.start_time);
+    UMA_HISTOGRAM_MEMORY_KB(
+        size_uma_name,
+        transaction_->transaction()->GetTransactionSize() / 1024);
+
     s = transaction_->CommitPhaseTwo();
     committed = s.ok();
   }