[Field trial params] Getting field trial params by feature name in Java.

chrome/browser/android/chrome_feature_list.cc

Index: chrome/browser/android/chrome_feature_list.cc
diff --git a/chrome/browser/android/chrome_feature_list.cc b/chrome/browser/android/chrome_feature_list.cc
index 44db12e45b0a2ee53ff076d1de20d206b417d051..13899d98653d1f9b0459f3698934b4afcf973411 100644
--- a/chrome/browser/android/chrome_feature_list.cc
+++ b/chrome/browser/android/chrome_feature_list.cc
@@ -21,7 +21,9 @@
 #include "jni/ChromeFeatureList_jni.h"
 
 using base::android::ConvertJavaStringToUTF8;
+using base::android::ConvertUTF8ToJavaString;
 using base::android::JavaParamRef;
+using base::android::ScopedJavaLocalRef;
 
 namespace chrome {
 namespace android {
@@ -157,6 +159,25 @@ static jboolean IsEnabled(JNIEnv* env,
   return false;
 }
 
+static ScopedJavaLocalRef<jstring> GetFieldTrialParamByFeature(
+    JNIEnv* env,
+    const JavaParamRef<jclass>& clazz,
+    const JavaParamRef<jstring>& jfeature_name,
+    const JavaParamRef<jstring>& jparam_name) {
+  const std::string feature_name = ConvertJavaStringToUTF8(env, jfeature_name);
+  const std::string param_name = ConvertJavaStringToUTF8(env, jparam_name);
+  for (size_t i = 0; i < arraysize(kFeaturesExposedToJava); ++i) {

[Alexei Svitkine (slow), 2017/02/08 16:36:00]

Nit: Since we loop over features in all of these functions, how about a helper
function to find the feature?

[jkrcal, 2017/02/09 10:00:45]

Good point, done!

+    if (kFeaturesExposedToJava[i]->name == feature_name) {
+      std::string param_value = base::GetFieldTrialParamValueByFeature(
+          *kFeaturesExposedToJava[i], param_name);
+      return ConvertUTF8ToJavaString(env, param_value);
+    }
+  }
+  // Features queried via this API must be present in |kFeaturesExposedToJava|.
+  NOTREACHED();
+  return ConvertUTF8ToJavaString(env, std::string());
+}
+
 static jint GetFieldTrialParamByFeatureAsInt(
     JNIEnv* env,
     const JavaParamRef<jclass>& clazz,
@@ -177,6 +198,46 @@ static jint GetFieldTrialParamByFeatureAsInt(
   return jdefault_value;
 }
 
+static jdouble GetFieldTrialParamByFeatureAsDouble(
+    JNIEnv* env,
+    const JavaParamRef<jclass>& clazz,
+    const JavaParamRef<jstring>& jfeature_name,
+    const JavaParamRef<jstring>& jparam_name,
+    const jdouble jdefault_value) {
+  const std::string feature_name = ConvertJavaStringToUTF8(env, jfeature_name);
+  const std::string param_name = ConvertJavaStringToUTF8(env, jparam_name);
+  double default_value = static_cast<double>(jdefault_value);
+
+  for (size_t i = 0; i < arraysize(kFeaturesExposedToJava); ++i) {
+    if (kFeaturesExposedToJava[i]->name == feature_name)
+      return base::GetFieldTrialParamByFeatureAsDouble(
+          *kFeaturesExposedToJava[i], param_name, default_value);
+  }
+  // Features queried via this API must be present in |kFeaturesExposedToJava|.
+  NOTREACHED();
+  return jdefault_value;
+}
+
+static jboolean GetFieldTrialParamByFeatureAsBoolean(
+    JNIEnv* env,
+    const JavaParamRef<jclass>& clazz,
+    const JavaParamRef<jstring>& jfeature_name,
+    const JavaParamRef<jstring>& jparam_name,
+    const jboolean jdefault_value) {
+  const std::string feature_name = ConvertJavaStringToUTF8(env, jfeature_name);
+  const std::string param_name = ConvertJavaStringToUTF8(env, jparam_name);
+  bool default_value = static_cast<bool>(jdefault_value);
+
+  for (size_t i = 0; i < arraysize(kFeaturesExposedToJava); ++i) {
+    if (kFeaturesExposedToJava[i]->name == feature_name)
+      return base::GetFieldTrialParamByFeatureAsBool(
+          *kFeaturesExposedToJava[i], param_name, default_value);
+  }
+  // Features queried via this API must be present in |kFeaturesExposedToJava|.
+  NOTREACHED();
+  return jdefault_value;
+}
+
 bool RegisterChromeFeatureListJni(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }