Serve fast NTP when experiment is enabled

chrome/browser/search/local_ntp_source.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/search/local_ntp_source.h"
 
 #include "base/json/json_string_value_serializer.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/metrics/field_trial.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/values.h"
 #include "chrome/browser/search/instant_io_context.h"
 #include "chrome/browser/search/search.h"
 #include "chrome/browser/search_engines/template_url_service_factory.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/grit/generated_resources.h"
 #include "components/search_engines/template_url_prepopulate_data.h"
@@ skipping 50 matching lines @@
     return false;
 
   const TemplateURL* default_provider =
       template_url_service->GetDefaultSearchProvider();
   return default_provider &&
       (TemplateURLPrepopulateData::GetEngineType(
           *default_provider, template_url_service->search_terms_data()) ==
        SEARCH_ENGINE_GOOGLE);
 }
 
+// Returns whether we are in the Fast NTP experiment or not.
+bool IsLocalNTPFastEnabled() {
+  return StartsWithASCII(base::FieldTrialList::FindFullName("LocalNTPFast"),
+                         "Enabled", true);
+}
+
+// Serves a particular resource.
+// Used for bypassing the default resources when we are in an experiment.
+void SendResource(int resource_id,
+                  const content::URLDataSource::GotDataCallback& callback) {
+  scoped_refptr<base::RefCountedStaticMemory> response(
+      ResourceBundle::GetSharedInstance().LoadDataResourceBytes(resource_id));
+  callback.Run(response.get());
+}
+
 // Adds a localized string keyed by resource id to the dictionary.
 void AddString(base::DictionaryValue* dictionary,
                const std::string& key,
                int resource_id) {
   dictionary->SetString(key, l10n_util::GetStringUTF16(resource_id));
 }
 
 // Adds a localized string for the Google searchbox placeholder text.
 void AddGoogleSearchboxPlaceholderString(base::DictionaryValue* dictionary) {
   base::string16 placeholder = l10n_util::GetStringFUTF16(
@@ skipping 67 matching lines @@
     const std::string& path,
     int render_process_id,
     int render_frame_id,
     const content::URLDataSource::GotDataCallback& callback) {
   const std::string stripped_path = StripParameters(path);
   if (stripped_path == kConfigDataFilename) {
     std::string config_data_js = GetConfigData(profile_);
     callback.Run(base::RefCountedString::TakeString(&config_data_js));
     return;
   }
+  if (IsLocalNTPFastEnabled()) {
+    if (stripped_path == "local-ntp.html") {
+      return SendResource(IDR_LOCAL_NTP_FAST_HTML, callback);
+    } else if (stripped_path == "local-ntp.js") {
+      return SendResource(IDR_LOCAL_NTP_FAST_JS, callback);
+    } else if (stripped_path == "local-ntp.css") {
+      return SendResource(IDR_LOCAL_NTP_FAST_CSS, callback);
+    }
+  }
   float scale = 1.0f;
   std::string filename;
   webui::ParsePathAndScale(
       GURL(GetLocalNtpPath() + stripped_path), &filename, &scale);
   ui::ScaleFactor scale_factor = ui::GetSupportedScaleFactor(scale);
   for (size_t i = 0; i < arraysize(kResources); ++i) {
     if (filename == kResources[i].filename) {
       scoped_refptr<base::RefCountedStaticMemory> response(
           ResourceBundle::GetSharedInstance().LoadDataResourceBytesForScale(
               kResources[i].identifier, scale_factor));
       callback.Run(response.get());
       return;
     }
   }
   callback.Run(NULL);
 }
 
 std::string LocalNtpSource::GetMimeType(
     const std::string& path) const {
-  const std::string& stripped_path = StripParameters(path);
-  std::string filename;
-  webui::ParsePathAndScale(GURL(GetLocalNtpPath() + stripped_path), &filename,
-                           NULL);
+  const std::string stripped_path = StripParameters(path);
   for (size_t i = 0; i < arraysize(kResources); ++i) {
-    if (filename == kResources[i].filename)
+    if (stripped_path == kResources[i].filename)
       return kResources[i].mime_type;
   }
   return std::string();
 }
 
 bool LocalNtpSource::ShouldServiceRequest(
     const net::URLRequest* request) const {
   DCHECK(request->url().host() == chrome::kChromeSearchLocalNtpHost);
   if (!InstantIOContext::ShouldServiceRequest(request))
     return false;
 
   if (request->url().SchemeIs(chrome::kChromeSearchScheme)) {
     std::string filename;
     webui::ParsePathAndScale(request->url(), &filename, NULL);
     for (size_t i = 0; i < arraysize(kResources); ++i) {
       if (filename == kResources[i].filename)
         return true;
     }
   }
   return false;
 }
 
 std::string LocalNtpSource::GetContentSecurityPolicyFrameSrc() const {
   // Allow embedding of most visited iframes.
   return base::StringPrintf("frame-src %s;",
                             chrome::kChromeSearchMostVisitedUrl);
 }