[sql] Record memory usage at various periods after startup.

This will be used to track improvements occuring from enabling
memory-mapped I/O.

BUG=489784

Review URL: https://codereview.chromium.org/1283033004

Cr-Commit-Position: refs/heads/master@{#343100}

sql/connection.cc

@@ -6,10 +6,12 @@
 
 #include <string.h>
 
+#include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
+#include "base/message_loop/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/strings/string_split.h"
@@ -111,6 +113,21 @@ bool ValidAttachmentPoint(const char* attachment_point) {
   return true;
 }
 
+void RecordSqliteMemory10Min() {
+  const int64 used = sqlite3_memory_used();
+  UMA_HISTOGRAM_COUNTS("Sqlite.MemoryKB.TenMinutes", used / 1024);
+}
+
+void RecordSqliteMemoryHour() {
+  const int64 used = sqlite3_memory_used();
+  UMA_HISTOGRAM_COUNTS("Sqlite.MemoryKB.OneHour", used / 1024);
+}
+
+void RecordSqliteMemoryDay() {
+  const int64 used = sqlite3_memory_used();
+  UMA_HISTOGRAM_COUNTS("Sqlite.MemoryKB.OneDay", used / 1024);
+}
+
 // SQLite automatically calls sqlite3_initialize() lazily, but
 // sqlite3_initialize() uses double-checked locking and thus can have
 // data races.
@@ -122,7 +139,26 @@ base::LazyInstance<base::Lock>::Leaky
     g_sqlite_init_lock = LAZY_INSTANCE_INITIALIZER;
 void InitializeSqlite() {
   base::AutoLock lock(g_sqlite_init_lock.Get());
-  sqlite3_initialize();
+  static bool first_call = true;
+  if (first_call) {
+    sqlite3_initialize();
+
+    // Schedule callback to record memory footprint histograms at 10m, 1h, and
+    // 1d.  There may not be a message loop in tests.
+    if (base::MessageLoop::current()) {
+      base::MessageLoop::current()->PostDelayedTask(
+          FROM_HERE, base::Bind(&RecordSqliteMemory10Min),
+          base::TimeDelta::FromMinutes(10));
+      base::MessageLoop::current()->PostDelayedTask(
+          FROM_HERE, base::Bind(&RecordSqliteMemoryHour),
+          base::TimeDelta::FromHours(1));
+      base::MessageLoop::current()->PostDelayedTask(
+          FROM_HERE, base::Bind(&RecordSqliteMemoryDay),
+          base::TimeDelta::FromDays(1));
+    }
+
+    first_call = false;
+  }
 }
 
 // Helper to get the sqlite3_file* associated with the "main" database.

tools/metrics/histograms/histograms.xml

@@ -42942,6 +42942,30 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>Error codes returned by sqlite for the history db.</summary>
 </histogram>
 
+<histogram name="Sqlite.MemoryKB.OneDay" units="KB">
+  <owner>shess@chromium.org</owner>
+  <summary>
+    SQLite memory footprint from sqlite3_memory_used() recorded 1 day after
+    first database is opened by sql::Connection.
+  </summary>
+</histogram>
+
+<histogram name="Sqlite.MemoryKB.OneHour" units="KB">
+  <owner>shess@chromium.org</owner>
+  <summary>
+    SQLite memory footprint from sqlite3_memory_used() recorded 1 hour after
+    first database is opened by sql::Connection.
+  </summary>
+</histogram>
+
+<histogram name="Sqlite.MemoryKB.TenMinutes" units="KB">
+  <owner>shess@chromium.org</owner>
+  <summary>
+    SQLite memory footprint from sqlite3_memory_used() recorded 10 minutes after
+    first database is opened by sql::Connection.
+  </summary>
+</histogram>
+
 <histogram name="Sqlite.Migration.History" units="milliseconds">
   <owner>shess@chromium.org</owner>
   <summary>