Get GWS ID from field trial

chrome/browser/android/data_usage/external_data_use_observer_bridge.cc

 // Copyright 2015 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/android/data_usage/external_data_use_observer_bridge.h"
 
 #include <memory>
 #include <vector>
 
 #include "base/android/context_utils.h"
 #include "base/android/jni_string.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/single_thread_task_runner.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/time/time.h"
 #include "chrome/browser/android/data_usage/data_use_tab_model.h"
 #include "chrome/browser/android/data_usage/external_data_use_observer.h"
 #include "chrome/browser/metrics/chrome_metrics_service_accessor.h"
 #include "components/variations/variations_associated_data.h"
 #include "content/public/browser/browser_thread.h"
 #include "jni/ExternalDataUseObserver_jni.h"
 
 using base::android::ConvertUTF8ToJavaString;
 
 namespace {
 
 // Name of the external data use observer synthetic field trial, enabled and
 // disabled groups.
 const char kSyntheticFieldTrial[] = "SyntheticExternalDataUseObserver";
 const char kSyntheticFieldTrialEnabledGroup[] = "Enabled";
 const char kSyntheticFieldTrialDisabledGroup[] = "Disabled";
 
 // Returns the package name of the control app from the field trial.
 const std::string GetControlAppPackageName() {
   return variations::GetVariationParamValue(
       chrome::android::ExternalDataUseObserver::
           kExternalDataUseObserverFieldTrial,
       "control_app_package_name");
 }
 
+// Returns the google variation ID from the field trial.
+variations::VariationID GetGoogleVariationID() {
+  variations::VariationID variation_id;
+  std::string variation_value = variations::GetVariationParamValue(
+      chrome::android::ExternalDataUseObserver::
+          kExternalDataUseObserverFieldTrial,
+      "variation_id");
+  if (!variation_value.empty() &&
+      base::StringToInt(variation_value, &variation_id)) {
+    return variation_id;
+  }
+  return variations::EMPTY_ID;
+}
+
 }  // namespace
 
 namespace chrome {
 
 namespace android {
 
 ExternalDataUseObserverBridge::ExternalDataUseObserverBridge()
     : construct_time_(base::TimeTicks::Now()),
       is_first_matching_rule_fetch_(true) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
@@ skipping 137 matching lines @@
 void ExternalDataUseObserverBridge::ShouldRegisterAsDataUseObserver(
     bool should_register) const {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(!j_external_data_use_observer_.is_null());
 
   io_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&ExternalDataUseObserver::ShouldRegisterAsDataUseObserver,
                  external_data_use_observer_, should_register));
 
-  // Set or clear the variation id for the enabled group.
-  JNIEnv* env = base::android::AttachCurrentThread();
-  variations::AssociateGoogleVariationID(
-      variations::GOOGLE_WEB_PROPERTIES, kSyntheticFieldTrial,
-      kSyntheticFieldTrialEnabledGroup,
-      should_register ? Java_ExternalDataUseObserver_getGoogleVariationID(
-                            env, j_external_data_use_observer_.obj())
-                      : variations::EMPTY_ID);
-  ChromeMetricsServiceAccessor::RegisterSyntheticFieldTrial(
-      kSyntheticFieldTrial, should_register
-                                ? kSyntheticFieldTrialEnabledGroup
-                                : kSyntheticFieldTrialDisabledGroup);
+  variations::VariationID variation_id = GetGoogleVariationID();
+  if (variation_id != variations::EMPTY_ID) {
+    // Set variation id for the enabled group if |should_register| is true.
+    // Otherwise clear the variation id for the enabled group by setting to
+    // EMPTY_ID.
+    variations::AssociateGoogleVariationID(
+        variations::GOOGLE_WEB_PROPERTIES, kSyntheticFieldTrial,
+        kSyntheticFieldTrialEnabledGroup,
+        should_register ? variation_id : variations::EMPTY_ID);
+    ChromeMetricsServiceAccessor::RegisterSyntheticFieldTrial(
+        kSyntheticFieldTrial, should_register
+                                  ? kSyntheticFieldTrialEnabledGroup
+                                  : kSyntheticFieldTrialDisabledGroup);
+  }
 }
 
 bool RegisterExternalDataUseObserver(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 }  // namespace android
 
 }  // namespace chrome