base: "implement" seek time detection for iOS/Android and add more stubs.

base/sys_info_freebsd.cc

Index: base/sys_info_freebsd.cc
diff --git a/base/sys_info_freebsd.cc b/base/sys_info_freebsd.cc
index 832b35985bedb4010a0130c3e6cf554a8ebbb265..338f1cd42d7a6a99a6783c661db52f654b63337c 100644
--- a/base/sys_info_freebsd.cc
+++ b/base/sys_info_freebsd.cc
@@ -22,6 +22,10 @@ int64 SysInfo::AmountOfPhysicalMemory() {
   return static_cast<int64>(pages) * page_size;
 }
 
+bool SysInfo::HasSeekPenalty(const FilePath& path, bool* has_seek_penalty) {
+  return false;
+}
+
 // static
 size_t SysInfo::MaxSharedMemorySize() {
   size_t limit;