Revert of Enforce lowercase switches when calling CommandLine::HasSwitch(const char*).

base/command_line.cc

Index: base/command_line.cc
diff --git a/base/command_line.cc b/base/command_line.cc
index 61ff5c10c3813e74ffdedece08cc0bf14638716a..3e143cc5d449f358936726f33c8d3fda95064f03 100644
--- a/base/command_line.cc
+++ b/base/command_line.cc
@@ -263,8 +263,7 @@
 }
 
 bool CommandLine::HasSwitch(const std::string& switch_string) const {
-  DCHECK_EQ(StringToLowerASCII(switch_string), switch_string);
-  return switches_.find(switch_string) != switches_.end();
+  return switches_.find(LowerASCIIOnWindows(switch_string)) != switches_.end();
 }
 
 bool CommandLine::HasSwitch(const char string_constant[]) const {