Expose a low-end device mode override flags for non-android OSs as well

base/sys_utils.cc

Index: base/sys_utils.cc
diff --git a/base/sys_utils.cc b/base/sys_utils.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e53dc9ce75614a78c656da7f632b6966b4b5b3ea
--- /dev/null
+++ b/base/sys_utils.cc
@@ -0,0 +1,54 @@
+// Copyright 2013 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 "base/sys_utils.h"
+
+#include "base/base_switches.h"
+#include "base/command_line.h"
+#include "base/lazy_instance.h"
+#include "base/sys_info.h"
+#include "base/sys_info_internal.h"
+
+#if !defined(OS_ANDROID)
+namespace {

[brettw, 2014/06/09 22:49:57]

blank lines around this, also check other namespaces in this file.

[c.shu, 2014/06/10 17:36:26]

Done.

+static const int kLowMemoryDeviceThresholdMB = 512;
+
+bool DetectLowEndDevice() {
+  CommandLine* command_line = CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kEnableLowEndDeviceMode )) {
+      return true;

[brettw, 2014/06/09 22:49:57]

Check indenting.

[c.shu, 2014/06/10 17:36:26]

Done.

+  }
+  if (command_line->HasSwitch(switches::kDisableLowEndDeviceMode)) {
+      return false;
+  }
+
+  if (command_line->HasSwitch(switches::kDetectLowEndDevice)) {
+    int ram_size_mb = base::SysInfo::AmountOfPhysicalMemoryMB();
+    return (ram_size_mb > 0 && ram_size_mb < kLowMemoryDeviceThresholdMB);
+  }
+  return false;
+}
+
+static base::LazyInstance<
+    base::internal::LazySysInfoValue<bool, DetectLowEndDevice> >::Leaky
+    g_lazy_low_end_device = LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+namespace base {
+// static
+bool SysUtils::IsLowEndDevice() {
+  return g_lazy_low_end_device.Get().value();

[brettw, 2014/06/09 22:49:57]

I think this leaky stuff is overkill for this use case. The singletons require a
lot of work and this is only a bool.

There is no problem with running the query multiple times in the case of a race
condition. I know this is OK on x86, does this also work on ARM? :
  static bool queried = false;
  static bool is_low_end = false;
  if (!queried) {
    is_low_end = Detect...
    queried = true
  }
  return is_low_end;

[ostap, 2014/06/10 17:05:57]

There are several places in base/sys-*.cc where LazyInstance is used for
primitive types. I would keep LazyInstance here for consistency.

+}
+}  // namespace base
+#endif
+
+namespace base {
+// static
+size_t SysUtils::AmountOfPhysicalMemoryKB() {
+  return SysInfo::AmountOfPhysicalMemory() / 1024;
+}
+
+SysUtils::SysUtils() { }
+}  // namespace base