Add simple cache backend experiment hidden behind a flag.

chrome/browser/chrome_browser_field_trials.cc

Index: chrome/browser/chrome_browser_field_trials.cc
diff --git a/chrome/browser/chrome_browser_field_trials.cc b/chrome/browser/chrome_browser_field_trials.cc
index 1c9a854e5c034f3c4c1a199cb271b27e3dab09aa..03f0ae491ab73750672a0cffc2b5e69adb554e66 100644
--- a/chrome/browser/chrome_browser_field_trials.cc
+++ b/chrome/browser/chrome_browser_field_trials.cc
@@ -59,6 +59,7 @@ ChromeBrowserFieldTrials::~ChromeBrowserFieldTrials() {
 void ChromeBrowserFieldTrials::SetupFieldTrials(
     const base::Time& install_time) {
   chrome_variations::SetupUniformityFieldTrials(install_time);
+  SetUpSimpleCacheFieldTrial();
 #if !defined(OS_ANDROID)
   SetupDesktopFieldTrials();
 #endif  // defined(OS_ANDROID)
@@ -191,6 +192,43 @@ void ChromeBrowserFieldTrials::DisableShowProfileSwitcherTrialIfNecessary() {
   }
 }
 
+// Sets up the experiment. The actual cache backend choice is made in the net/
+// internals by looking at the experiment state.
+void ChromeBrowserFieldTrials::SetUpSimpleCacheFieldTrial() {
+  if (parsed_command_line_.HasSwitch(switches::kUseSimpleCacheBackend)) {
+    const std::string opt_value = parsed_command_line_.GetSwitchValueASCII(
+        switches::kUseSimpleCacheBackend);
+    if (LowerCaseEqualsASCII(opt_value, "off")) {
+      // This is the default.
+      return;
+    }
+    const base::FieldTrial::Probability kDivisor = 100;
+    scoped_refptr<base::FieldTrial> trial(
+        base::FieldTrialList::FactoryGetFieldTrial("SimpleCacheTrial", kDivisor,
+                                                   "No", 2013, 12, 31, NULL));
+    trial->UseOneTimeRandomization();
+    if (LowerCaseEqualsASCII(opt_value, "on")) {
+      trial->AppendGroup("Yes", 100);
+      return;
+    }
+#if defined(OS_ANDROID)
+    if (LowerCaseEqualsASCII(opt_value, "experiment")) {
+      // TODO(pasko): Make this the default on Android when the simple cache
+      // adds a few more necessary features. Also adjust the probability.
+      const base::FieldTrial::Probability simple_cache_probability = 1;

[rvargas (doing something else), 2013/03/15 19:16:25]

nit: name as a constant

+      trial->AppendGroup("Yes", simple_cache_probability);
+      trial->AppendGroup("Control", simple_cache_probability);
+      trial->group();
+      return;
+    }
+    CHECK(0) << "Only values (on|off|experiment) are supported for option "
+             << switches::kUseSimpleCacheBackend << ".";
+#endif
+    CHECK(0) << "Only values (on|off) are supported for option "
+             << switches::kUseSimpleCacheBackend << ".";
+  }
+}
+
 void ChromeBrowserFieldTrials::SetUpCacheSensitivityAnalysisFieldTrial() {
   const base::FieldTrial::Probability kDivisor = 100;