Free jobjects inside loop

We have limited number of jni local references, leaking jobjects inside
loop may cause local reference table to overflow.

Bug: 726426
Change-Id: I4b1ffc9fcb74d1a78d0415f9d9c79533facb7839
Reviewed-on: https://chromium-review.googlesource.com/895843
Commit-Queue: Ran Ji <ranj@chromium.org>
Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533744}

chrome/browser/android/provider/chrome_browser_provider.cc

@@ -142,8 +142,9 @@ std::vector<base::string16> ConvertJStringArrayToString16Array(
   if (array) {
     jsize len = env->GetArrayLength(array);
     for (int i = 0; i < len; i++) {
-      results.push_back(ConvertJavaStringToUTF16(env,
-          static_cast<jstring>(env->GetObjectArrayElement(array, i))));
+      ScopedJavaLocalRef<jstring> j_str(
+          env, static_cast<jstring>(env->GetObjectArrayElement(array, i)));
+      results.push_back(ConvertJavaStringToUTF16(env, j_str));
     }
   }
   return results;
@@ -939,8 +940,9 @@ ScopedJavaLocalRef<jobject> ChromeBrowserProvider::QueryBookmarkFromAPI(
   if (projection) {
     jsize len = env->GetArrayLength(projection);
     for (int i = 0; i < len; i++) {
-      std::string name = ConvertJavaStringToUTF8(env, static_cast<jstring>(
-          env->GetObjectArrayElement(projection, i)));
+      ScopedJavaLocalRef<jstring> j_name(
+          env, static_cast<jstring>(env->GetObjectArrayElement(projection, i)));
+      std::string name = ConvertJavaStringToUTF8(env, j_name);
       history::HistoryAndBookmarkRow::ColumnID id =
           history::HistoryAndBookmarkRow::GetColumnID(name);
       if (id == history::HistoryAndBookmarkRow::COLUMN_END) {
@@ -1080,8 +1082,9 @@ ScopedJavaLocalRef<jobject> ChromeBrowserProvider::QuerySearchTermFromAPI(
   if (projection) {
     jsize len = env->GetArrayLength(projection);
     for (int i = 0; i < len; i++) {
-      std::string name = ConvertJavaStringToUTF8(env, static_cast<jstring>(
-          env->GetObjectArrayElement(projection, i)));
+      ScopedJavaLocalRef<jstring> j_name(
+          env, static_cast<jstring>(env->GetObjectArrayElement(projection, i)));
+      std::string name = ConvertJavaStringToUTF8(env, j_name);
       history::SearchRow::ColumnID id =
           history::SearchRow::GetColumnID(name);
       if (id == history::SearchRow::COLUMN_END) {

components/policy/core/browser/android/policy_converter.cc

@@ -95,9 +95,9 @@ PolicyConverter::ConvertJavaStringArrayToListValue(
 
   std::unique_ptr<base::ListValue> list_value(new base::ListValue());
   for (int i = 0; i < length; ++i) {
-    jstring str =
-        static_cast<jstring>(env->GetObjectArrayElement(array.obj(), i));
-    list_value->AppendString(ConvertJavaStringToUTF8(env, str));
+    base::android::ScopedJavaLocalRef<jstring> j_str(
+        env, static_cast<jstring>(env->GetObjectArrayElement(array.obj(), i)));
+    list_value->AppendString(ConvertJavaStringToUTF8(env, j_str));
   }
 
   return list_value;

components/sync/test/fake_server/android/fake_server_helper_android.cc

@@ -90,8 +90,9 @@ jboolean FakeServerHelperAndroid::VerifySessions(
     const JavaParamRef<jobjectArray>& url_array) {
   std::multiset<std::string> tab_urls;
   for (int i = 0; i < env->GetArrayLength(url_array); i++) {
-    jstring s = (jstring)env->GetObjectArrayElement(url_array, i);
-    tab_urls.insert(base::android::ConvertJavaStringToUTF8(env, s));
+    base::android::ScopedJavaLocalRef<jstring> j_string(
+        env, static_cast<jstring>(env->GetObjectArrayElement(url_array, i)));
+    tab_urls.insert(base::android::ConvertJavaStringToUTF8(env, j_string));
   }
   fake_server::SessionsHierarchy expected_sessions;
   expected_sessions.AddWindow(tab_urls);

media/midi/midi_device_android.cc

@@ -35,17 +35,20 @@ MidiDeviceAndroid::MidiDeviceAndroid(JNIEnv* env,
   jsize num_input_ports = env->GetArrayLength(raw_input_ports.obj());
 
   for (jsize i = 0; i < num_input_ports; ++i) {
-    jobject port = env->GetObjectArrayElement(raw_input_ports.obj(), i);
+    ScopedJavaLocalRef<jobject> j_port(
+        env, env->GetObjectArrayElement(raw_input_ports.obj(), i));
     input_ports_.push_back(
-        std::make_unique<MidiInputPortAndroid>(env, port, delegate));
+        std::make_unique<MidiInputPortAndroid>(env, j_port.obj(), delegate));
   }
 
   ScopedJavaLocalRef<jobjectArray> raw_output_ports =
       Java_MidiDeviceAndroid_getOutputPorts(env, raw_device);
   jsize num_output_ports = env->GetArrayLength(raw_output_ports.obj());
   for (jsize i = 0; i < num_output_ports; ++i) {
-    jobject port = env->GetObjectArrayElement(raw_output_ports.obj(), i);
-    output_ports_.push_back(std::make_unique<MidiOutputPortAndroid>(env, port));
+    ScopedJavaLocalRef<jobject> j_port(
+        env, env->GetObjectArrayElement(raw_output_ports.obj(), i));
+    output_ports_.push_back(
+        std::make_unique<MidiOutputPortAndroid>(env, j_port.obj()));
   }
 }