Make task manager memory data more efficient and meaningful.

chrome/browser/private_working_set_snapshot_win_unittest.cc

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/private_working_set_snapshot.h"
+
+#include "base/win/windows_version.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using PrivateWorkingSetSnapshotWinTest = testing::Test;
+
+TEST_F(PrivateWorkingSetSnapshotWinTest, FindPidSelfTest) {
+  // The Pdh APIs are supported on Windows XP and above, but the "Working Set -
+  // Private" counter that PrivateWorkingSetSnapshot depends on is not defined
+  // until Windows Vista and is not reliable until Windows 7. Early-out to avoid
+  // test failure.
+  if (base::win::GetVersion() <= base::win::VERSION_VISTA)
+    return;
+
+  // Sample this process.
+  base::ProcessId pid = base::GetCurrentProcId();
+
+  PrivateWorkingSetSnapshot private_ws_snapshot;
+
+  private_ws_snapshot.AddToMonitorList("unit_tests");
+  private_ws_snapshot.Sample();
+
+  size_t private_ws = private_ws_snapshot.GetPrivateWorkingSet(pid);
+  // Private working set is difficult to predict but should be at least several
+  // MB. Initial tests show a value of 19+ MB depending on how many tests and
+  // processes are used. Anomalously small or large values would warrant
+  // investigation.
+  EXPECT_GT(private_ws, 2000000u);
+  // Check that the WS is less than 1500 MB. This is set very high to reduce the
+  // chance that unrelated changes could ever make this fail. This mostly just
+  // checks against some uncaught error that might return 0xFFFFFFFF. When run
+  // under Dr Memory the private working set was seen to be about 850 MB, which
+  // is why such a high threshold has been chosen.
+  EXPECT_LT(private_ws, 1500000000u);
+
+  // Allocate and touch a large block of memory (vector's constructor will zero
+  // every entry). This will increase the private working set.
+  const size_t alloc_size = 10000000;
+  std::vector<char> big_memory(alloc_size);
+
+  size_t private_ws2 = private_ws_snapshot.GetPrivateWorkingSet(pid);
+  EXPECT_EQ(private_ws, private_ws2) << "GetPrivateWorkingSet should be "
+                                        "consistent until the next call to "
+                                        "Sample()";
+
+  private_ws_snapshot.Sample();
+  size_t private_ws3 = private_ws_snapshot.GetPrivateWorkingSet(pid);
+  EXPECT_GT(private_ws3, private_ws2 + alloc_size / 2)
+      << "GetPrivateWorkingSet should increase as we allocate more memory";
+}