Revert of Enforce lowercase switches when calling CommandLine::HasSwitch(const char*). (patchset #5 id:80001 of https://codereview.chromium.org/1046363002/)

Reason for revert:
This causes test fails on Android:
https://build.chromium.org/p/chromium.linux/builders/Android%20Tests%20%28dbg%29/builds/27294

The test uses upper case with HasSwitch():
https://code.google.com/p/chromium/codesearch#chromium/src/content/public/android/javatests/src/org/chromium/content/browser/ContentCommandLineTest.java&q=testJavaNativeTransition&sq=package:chromium&type=cs&l=96

Original issue's description:
> Enforce lowercase switches when calling CommandLine::HasSwitch.
>
> At the moment, all compile-time switches are lowercase. By enforcing
> this, we can skip converting it to lowercase on Windows, which saves
> one string allocation per call.
>
> On a profile with 2 extensions, HasSwitch is called ~12k times during
> startup. In an ideal situation (no paging/cache pressure), the
> string allocation under Windows takes ~137ns on an Xeon E5-2690 @
> 2.9Ghz. So this should shave off at least 1.6ms off a typical startup
> with this hardware. For context,
> Startup.BrowserMessageLoopStartTimeFromMainEntry is typically
> 280-300ms on the same hardware, so we should get a ~0.5% improvement.
>
> BUG=472383
>
> Committed: https://crrev.com/f58961749a980032241fe6c3fc829ac2e6652030
> Cr-Commit-Position: refs/heads/master@{#325576}

TBR=tapted@chromium.org,brettw@chromium.org,jackhou@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=472383

Review URL: https://codereview.chromium.org/1091993002

Cr-Commit-Position: refs/heads/master@{#325610}

3 files changed, 7 insertions, 8 deletions

diff --git a/base/command_line.cc b/base/command_line.cc
index 61ff5c1..3e143cc 100644
--- a/base/command_line.cc
+++ b/base/command_line.cc
@@ -263,8 +263,7 @@ void CommandLine::SetProgram(const FilePath& program) {
 }
 
 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 {
diff --git a/base/command_line.h b/base/command_line.h
index 439921e..19df40c 100644
--- a/base/command_line.h
+++ b/base/command_line.h
@@ -142,7 +142,7 @@ class BASE_EXPORT CommandLine {
   void SetProgram(const FilePath& program);
 
   // Returns true if this command line contains the given switch.
-  // Switch names should only be lowercase.
+  // (Switch names are case-insensitive).
   // The second override provides an optimized version to avoid inlining the
   // codegen for the string allocation.
   bool HasSwitch(const std::string& switch_string) const;
diff --git a/base/command_line_unittest.cc b/base/command_line_unittest.cc
index db1a0b2..e395c856 100644
--- a/base/command_line_unittest.cc
+++ b/base/command_line_unittest.cc
@@ -60,13 +60,12 @@ TEST(CommandLineTest, CommandLineConstructor) {
             cl.GetProgram().value());
 
   EXPECT_TRUE(cl.HasSwitch("foo"));
-#if defined(OS_WIN)
-  EXPECT_TRUE(cl.HasSwitch("bar"));
-#else
-  EXPECT_FALSE(cl.HasSwitch("bar"));
-#endif
+  EXPECT_TRUE(cl.HasSwitch("bAr"));
   EXPECT_TRUE(cl.HasSwitch("baz"));
   EXPECT_TRUE(cl.HasSwitch("spaetzle"));
+#if defined(OS_WIN)
+  EXPECT_TRUE(cl.HasSwitch("SPAETZLE"));
+#endif
   EXPECT_TRUE(cl.HasSwitch("other-switches"));
   EXPECT_TRUE(cl.HasSwitch("input-translation"));
 
@@ -129,6 +128,7 @@ TEST(CommandLineTest, CommandLineFromString) {
   EXPECT_TRUE(cl.HasSwitch("bar"));
   EXPECT_TRUE(cl.HasSwitch("baz"));
   EXPECT_TRUE(cl.HasSwitch("spaetzle"));
+  EXPECT_TRUE(cl.HasSwitch("SPAETZLE"));
   EXPECT_TRUE(cl.HasSwitch("other-switches"));
   EXPECT_TRUE(cl.HasSwitch("input-translation"));
   EXPECT_TRUE(cl.HasSwitch("quotes"));