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

base/sys_info_chromeos.cc

Index: base/sys_info_chromeos.cc
diff --git a/base/sys_info_chromeos.cc b/base/sys_info_chromeos.cc
index ef5f1fedb51d576a69d1503c583dcc80f5d29e1f..2a5f5d74043e581e7b6733baf0737d517a226775 100644
--- a/base/sys_info_chromeos.cc
+++ b/base/sys_info_chromeos.cc
@@ -169,6 +169,11 @@ ChromeOSVersionInfo& GetChromeOSVersionInfo() {
 
 }  // namespace
 
+bool SysInfo::HasSeekPenalty(const FilePath& path, bool* has_seek_penalty) {
+  // TODO(dbeam): implement. Can we just use boards/models?
+  return false;
+}
+
 // static
 void SysInfo::OperatingSystemVersionNumbers(int32* major_version,
                                             int32* minor_version,