Adding disable option to prerender from omnibox switch.

BUG=
TEST=


Review URL: http://codereview.chromium.org/8200016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@104898 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 77 insertions, 38 deletions

diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index 4d65aec..ffd709e 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -4597,6 +4597,15 @@ Keep your key file in a safe place. You will need it to create new versions of y
       <message name="IDS_FLAGS_PRERENDER_FROM_OMNIBOX_DESCRIPTION" desc="Description for the flag to prerender from the omnibox">
         Enables prerendering of suggestions from the Omnibox and predicts appropriate network actions (prerendering, Instant, DNS preconnect) by calculating a confidence value for each Omnibox result.
       </message>
+      <message name="IDS_FLAGS_PRERENDER_FROM_OMNIBOX_AUTOMATIC" desc="Option name for automatic selection in the Prerendering from Omnibox lab">
+        Automatic
+      </message>
+      <message name="IDS_FLAGS_PRERENDER_FROM_OMNIBOX_ENABLED" desc="Option name for always enabling Prerendering from the Omnibox">
+        Enabled
+      </message>
+      <message name="IDS_FLAGS_PRERENDER_FROM_OMNIBOX_DISABLED" desc="Option name for always disabling Prerendering from Omnibox">
+        Disabled
+      </message>
       <message name="IDS_FLAGS_ENABLE_ADDITIONAL_AUTOFILL_FEEDBACK_NAME" desc="Title for the flag to enable prompts for Autofill feedback">
         Send additional Autofill feedback
       </message>
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index d07427e..571e8f6 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -45,6 +45,14 @@ const char kMediaPlayerExperimentName[] = "media-player";
 const char kAdvancedFileSystemExperimentName[] = "advanced-file-system";
 const char kVerticalTabsExperimentName[] = "vertical-tabs";
 
+const Experiment::Choice kPrerenderFromOmniboxChoices[] = {
+  { IDS_FLAGS_PRERENDER_FROM_OMNIBOX_AUTOMATIC, "", "" },
+  { IDS_FLAGS_PRERENDER_FROM_OMNIBOX_ENABLED, switches::kPrerenderFromOmnibox,
+    switches::kPrerenderFromOmniboxSwitchValueEnabled },
+  { IDS_FLAGS_PRERENDER_FROM_OMNIBOX_DISABLED, switches::kPrerenderFromOmnibox,
+    switches::kPrerenderFromOmniboxSwitchValueDisabled }
+};
+
 // RECORDING USER METRICS FOR FLAGS:
 // -----------------------------------------------------------------------------
 // The first line of the experiment is the internal name. If you'd like to
@@ -327,7 +335,7 @@ const Experiment kExperiments[] = {
     IDS_FLAGS_PRERENDER_FROM_OMNIBOX_NAME,
     IDS_FLAGS_PRERENDER_FROM_OMNIBOX_DESCRIPTION,
     kOsAll,
-    SINGLE_VALUE_TYPE(switches::kPrerenderFromOmnibox)
+    MULTI_VALUE_TYPE(kPrerenderFromOmniboxChoices)
   },
   {
     "panels",
diff --git a/chrome/browser/prerender/prerender_browsertest.cc b/chrome/browser/prerender/prerender_browsertest.cc
index 626e9c1..63684d5 100644
--- a/chrome/browser/prerender/prerender_browsertest.cc
+++ b/chrome/browser/prerender/prerender_browsertest.cc
@@ -421,8 +421,8 @@ class PrerenderBrowserTest : public InProcessBrowserTest {
   }
 
   virtual void SetUpCommandLine(CommandLine* command_line) OVERRIDE {
-    command_line->AppendSwitchASCII(switches::kPrerender,
-                                    switches::kPrerenderSwitchValueEnabled);
+    command_line->AppendSwitchASCII(switches::kPrerenderMode,
+                                    switches::kPrerenderModeSwitchValueEnabled);
     // This is needed to enable click-to-play without triggering a DCHECK.
     // It does not actually enable click-to-play.
     command_line->AppendSwitchASCII(switches::kEnableClickToPlay, "");
diff --git a/chrome/browser/prerender/prerender_field_trial.cc b/chrome/browser/prerender/prerender_field_trial.cc
index 2402329..f87ad07 100644
--- a/chrome/browser/prerender/prerender_field_trial.cc
+++ b/chrome/browser/prerender/prerender_field_trial.cc
@@ -37,8 +37,6 @@ const char* NameFromOmniboxHeuristic(OmniboxHeuristic heuristic) {
 
 }  // end namespace
 
-// If the command line contains the --prerender-from-omnibox switch, enable
-// prerendering from the Omnibox. If not, enter the user into a field trial.
 void ConfigurePrerenderFromOmnibox();
 
 void ConfigurePrefetchAndPrerender(const CommandLine& command_line) {
@@ -50,20 +48,21 @@ void ConfigurePrefetchAndPrerender(const CommandLine& command_line) {
   };
 
   PrerenderOption prerender_option = PRERENDER_OPTION_AUTO;
-  if (command_line.HasSwitch(switches::kPrerender)) {
+  if (command_line.HasSwitch(switches::kPrerenderMode)) {
     const std::string switch_value =
-        command_line.GetSwitchValueASCII(switches::kPrerender);
+        command_line.GetSwitchValueASCII(switches::kPrerenderMode);
 
-    if (switch_value == switches::kPrerenderSwitchValueAuto) {
+    if (switch_value == switches::kPrerenderModeSwitchValueAuto) {
       prerender_option = PRERENDER_OPTION_AUTO;
-    } else if (switch_value == switches::kPrerenderSwitchValueDisabled) {
+    } else if (switch_value == switches::kPrerenderModeSwitchValueDisabled) {
       prerender_option = PRERENDER_OPTION_DISABLED;
     } else if (switch_value.empty() ||
-               switch_value == switches::kPrerenderSwitchValueEnabled) {
+               switch_value == switches::kPrerenderModeSwitchValueEnabled) {
       // The empty string means the option was provided with no value, and that
       // means enable.
       prerender_option = PRERENDER_OPTION_ENABLED;
-    } else if (switch_value == switches::kPrerenderSwitchValuePrefetchOnly) {
+    } else if (switch_value ==
+               switches::kPrerenderModeSwitchValuePrefetchOnly) {
       prerender_option = PRERENDER_OPTION_PREFETCH_ONLY;
     } else {
       prerender_option = PRERENDER_OPTION_DISABLED;
@@ -141,23 +140,22 @@ void ConfigurePrefetchAndPrerender(const CommandLine& command_line) {
 void ConfigurePrerenderFromOmnibox() {
   // Field trial to see if we're enabled.
   const base::FieldTrial::Probability kDivisor = 100;
-  if (!CommandLine::ForCurrentProcess()->HasSwitch(
-      switches::kPrerenderFromOmnibox)) {
-    const base::FieldTrial::Probability kEnabledProbability = 40;
-    scoped_refptr<base::FieldTrial> trial(
-        new base::FieldTrial("PrerenderFromOmnibox", kDivisor,
-                             "OmniboxPrerenderDisabled", 2012, 8, 30));
-    trial->AppendGroup("OmniboxPrerenderEnabled", kEnabledProbability);
-  }
+
+  const base::FieldTrial::Probability kEnabledProbability = 40;
+  scoped_refptr<base::FieldTrial> enabled_trial(
+      new base::FieldTrial("PrerenderFromOmnibox", kDivisor,
+                           "OmniboxPrerenderDisabled", 2012, 8, 30));
+  enabled_trial->AppendGroup("OmniboxPrerenderEnabled", kEnabledProbability);
 
   // Field trial to see which heuristic to use.
   const base::FieldTrial::Probability kConservativeProbability = 50;
-  scoped_refptr<base::FieldTrial> trial(
+  scoped_refptr<base::FieldTrial> heuristic_trial(
       new base::FieldTrial("PrerenderFromOmniboxHeuristic", kDivisor,
                            "OriginalAlgorithm", 2012, 8, 30));
   omnibox_original_group_id = base::FieldTrial::kDefaultGroupNumber;
   omnibox_conservative_group_id =
-      trial->AppendGroup("ConservativeAlgorithm", kConservativeProbability);
+      heuristic_trial->AppendGroup("ConservativeAlgorithm",
+                                   kConservativeProbability);
 }
 
 bool IsOmniboxEnabled(Profile* profile) {
@@ -167,9 +165,21 @@ bool IsOmniboxEnabled(Profile* profile) {
   if (!PrerenderManager::IsPrerenderingPossible())
     return false;
 
+  // Override any field trial groups if the user has set a command line flag.
   if (CommandLine::ForCurrentProcess()->HasSwitch(
-      switches::kPrerenderFromOmnibox))
-    return true;
+      switches::kPrerenderFromOmnibox)) {
+    const std::string switch_value =
+        CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+            switches::kPrerenderFromOmnibox);
+
+    if (switch_value == switches::kPrerenderFromOmniboxSwitchValueEnabled)
+      return true;
+
+    if (switch_value == switches::kPrerenderFromOmniboxSwitchValueDisabled)
+      return false;
+
+    DCHECK(switch_value == switches::kPrerenderFromOmniboxSwitchValueAuto);
+  }
 
   if (!MetricsServiceHelper::IsMetricsReportingEnabled())
     return false;
diff --git a/chrome/browser/ui/webui/net_internals_ui_browsertest.cc b/chrome/browser/ui/webui/net_internals_ui_browsertest.cc
index 6cc683b..f3fa3e1 100644
--- a/chrome/browser/ui/webui/net_internals_ui_browsertest.cc
+++ b/chrome/browser/ui/webui/net_internals_ui_browsertest.cc
@@ -97,8 +97,8 @@ NetInternalsTest::~NetInternalsTest() {
 void NetInternalsTest::SetUpCommandLine(CommandLine* command_line) {
   WebUIBrowserTest::SetUpCommandLine(command_line);
   // Needed to test the prerender view.
-  command_line->AppendSwitchASCII(switches::kPrerender,
-                                  switches::kPrerenderSwitchValueEnabled);
+  command_line->AppendSwitchASCII(switches::kPrerenderMode,
+                                  switches::kPrerenderModeSwitchValueEnabled);
 }
 
 void NetInternalsTest::SetUpInProcessBrowserTestFixture() {
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index 14f5394..7cc1f65 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -823,22 +823,31 @@ const char kPpapiFlashInProcess[]          = "ppapi-flash-in-process";
 // Instant for faster searching and browsing" in Preferences -> Basics).
 const char kPreloadInstantSearch[]          = "preload-instant-search";
 
-// Controls speculative prerendering of pages, and content prefetching.  Both
-// are dispatched from <link rel=prefetch href=...> elements.
-const char kPrerender[]                     = "prerender";
 // Trigger prerendering of pages from suggestions in the omnibox. Only has an
 // effect when Instant is either disabled or restricted to search, and when
 // prerender is enabled.
 const char kPrerenderFromOmnibox[]          = "prerender-from-omnibox";
-// These are the values the switch may have, as in "--prerender=auto".
+// These are the values the kPrerenderFromOmnibox switch may have, as in
+// "--prerender-from-omnibox=auto".
+//   auto: Allow field trial selection.
+const char kPrerenderFromOmniboxSwitchValueAuto[] = "auto";
+//   disabled: No prerendering.
+const char kPrerenderFromOmniboxSwitchValueDisabled[] = "disabled";
+//   enabled: Guaranteed prerendering.
+const char kPrerenderFromOmniboxSwitchValueEnabled[] = "enabled";
+// Controls speculative prerendering of pages, and content prefetching.  Both
+// are dispatched from <link rel=prefetch href=...> elements.
+const char kPrerenderMode[]                     = "prerender";
+// These are the values the kPrerenderMode switch may have, as in
+// "--prerender=auto".
 //   auto: Allow field trial selection in both prerender and prefetch.
-const char kPrerenderSwitchValueAuto[]      = "auto";
+const char kPrerenderModeSwitchValueAuto[]      = "auto";
 //   disabled: No prerendering or prefetching.
-const char kPrerenderSwitchValueDisabled[]  = "disabled";
+const char kPrerenderModeSwitchValueDisabled[]  = "disabled";
 //   enabled: Both prerendering and prefetching.
-const char kPrerenderSwitchValueEnabled[]   = "enabled";
+const char kPrerenderModeSwitchValueEnabled[]   = "enabled";
 //   prefetch_only: No prerendering, but enable prefetching.
-const char kPrerenderSwitchValuePrefetchOnly[] = "prefetch_only";
+const char kPrerenderModeSwitchValuePrefetchOnly[] = "prefetch_only";
 
 // Prints the pages on the screen.
 const char kPrint[]                         = "print";
diff --git a/chrome/common/chrome_switches.h b/chrome/common/chrome_switches.h
index 872136d..e5be0af 100644
--- a/chrome/common/chrome_switches.h
+++ b/chrome/common/chrome_switches.h
@@ -227,12 +227,15 @@ extern const char kPackExtensionKey[];
 extern const char kParentProfile[];
 extern const char kPpapiFlashInProcess[];
 extern const char kPreloadInstantSearch[];
-extern const char kPrerender[];
 extern const char kPrerenderFromOmnibox[];
-extern const char kPrerenderSwitchValueAuto[];
-extern const char kPrerenderSwitchValueDisabled[];
-extern const char kPrerenderSwitchValueEnabled[];
-extern const char kPrerenderSwitchValuePrefetchOnly[];
+extern const char kPrerenderFromOmniboxSwitchValueAuto[];
+extern const char kPrerenderFromOmniboxSwitchValueDisabled[];
+extern const char kPrerenderFromOmniboxSwitchValueEnabled[];
+extern const char kPrerenderMode[];
+extern const char kPrerenderModeSwitchValueAuto[];
+extern const char kPrerenderModeSwitchValueDisabled[];
+extern const char kPrerenderModeSwitchValueEnabled[];
+extern const char kPrerenderModeSwitchValuePrefetchOnly[];
 extern const char kPrint[];
 extern const char kProductVersion[];
 extern const char kProfileDirectory[];