Fix a crash when cameraInfo is NULL

It is possible that cameraInfo returns NULL.
However, the NULL case is not well handled and it will cause crashes.
This change also removed the unncessary JNI call to convert an int to string

BUG=424775

Review URL: https://codereview.chromium.org/667433003

Cr-Commit-Position: refs/heads/master@{#300578}

media/base/android/java/src/org/chromium/media/VideoCaptureAndroid.java

@@ -85,6 +85,7 @@ public class VideoCaptureAndroid extends VideoCapture {
 
     static String getName(int id) {
         android.hardware.Camera.CameraInfo cameraInfo = VideoCapture.getCameraInfo(id);
+        if (cameraInfo == null) return null;
         return "camera " + id + ", facing " + (cameraInfo.facing ==
                 android.hardware.Camera.CameraInfo.CAMERA_FACING_FRONT ? "front" : "back");
     }

media/base/android/java/src/org/chromium/media/VideoCaptureFactory.java

@@ -107,11 +107,6 @@ class VideoCaptureFactory {
                 VideoCaptureAndroid.getName(id);
     }
 
-    @CalledByNative
-    static String getDeviceId(int id) {
-        return Integer.toString(id);
-    }
-
     @CalledByNative
     static VideoCapture.CaptureFormat[] getDeviceSupportedFormats(int id) {
         return ChromiumCameraInfo.isSpecialCamera(id) ?

media/video/capture/android/video_capture_device_factory_android.cc

@@ -65,11 +65,14 @@ void VideoCaptureDeviceFactoryAndroid::GetDeviceNames(
     return;
 
   for (int camera_id = num_cameras - 1; camera_id >= 0; --camera_id) {
+    base::android::ScopedJavaLocalRef<jstring> device_name =
+        Java_VideoCaptureFactory_getDeviceName(env, camera_id);
+    if (device_name.obj() == NULL)
+      continue;
+
     VideoCaptureDevice::Name name(
-        base::android::ConvertJavaStringToUTF8(
-            Java_VideoCaptureFactory_getDeviceName(env, camera_id)),
-        base::android::ConvertJavaStringToUTF8(
-            Java_VideoCaptureFactory_getDeviceId(env, camera_id)));
+        base::android::ConvertJavaStringToUTF8(device_name),
+        base::IntToString(camera_id));
     device_names->push_back(name);
 
     DVLOG(1) << "VideoCaptureDeviceFactoryAndroid::GetDeviceNames: camera "