Add systemInfo.memory API implementation


BUG=136519
TEST=browser_tests --gtest_filter=SystemInfoMemoryApiTest.*

Review URL: https://chromiumcodereview.appspot.com/11185049

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@164518 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/base/sys_info_mac.cc b/base/sys_info_mac.cc
index 8ed0290..23931869 100644
--- a/base/sys_info_mac.cc
+++ b/base/sys_info_mac.cc
@@ -59,6 +59,12 @@
 }
 
 // static
+int64 SysInfo::AmountOfAvailablePhysicalMemory() {
+  // TODO(hongbo): Add implementation for Mac.
+  return 0;
+}
+
+// static
 std::string SysInfo::CPUModelName() {
   char name[256];
   size_t len = arraysize(name);