Android: cleans up hand-written JNI for video_capture_device_android.cc

It's dangerous to rely on hand-written, run-time binding for JNI.
By wrapping the usage in a thin class, we get build-time type-safety.
It also clarifies the boundaries, and make the code on each side clearer.

BUG=


Review URL: https://chromiumcodereview.appspot.com/12604003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@187295 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 51 insertions, 50 deletions

diff --git a/media/base/android/java/src/org/chromium/media/VideoCapture.java b/media/base/android/java/src/org/chromium/media/VideoCapture.java
index 4f66ef6..0266558 100644
--- a/media/base/android/java/src/org/chromium/media/VideoCapture.java
+++ b/media/base/android/java/src/org/chromium/media/VideoCapture.java
@@ -135,7 +135,8 @@ public class VideoCapture implements PreviewCallback, OnFrameAvailableListener {
                 }
             }
             if (minDiff == Integer.MAX_VALUE) {
-                Log.e(TAG, "allocate: can not find a resolution whose width is multiple of 32");
+                Log.e(TAG, "allocate: can not find a resolution whose width " +
+                           "is multiple of 32");
                 return false;
             }
             mCurrentCapability.mWidth = matchedWidth;
@@ -304,6 +305,44 @@ public class VideoCapture implements PreviewCallback, OnFrameAvailableListener {
     @Override
     public void onFrameAvailable(SurfaceTexture surfaceTexture) { }
 
+    private static class ChromiumCameraInfo {
+        private final int mId;
+        private final Camera.CameraInfo mCameraInfo;
+
+        private ChromiumCameraInfo(int index) {
+            mId = index;
+            mCameraInfo = new Camera.CameraInfo();
+            Camera.getCameraInfo(index, mCameraInfo);
+        }
+
+        @CalledByNative("ChromiumCameraInfo")
+        private static int getNumberOfCameras() {
+            return Camera.getNumberOfCameras();
+        }
+
+        @CalledByNative("ChromiumCameraInfo")
+        private static ChromiumCameraInfo getAt(int index) {
+            return new ChromiumCameraInfo(index);
+        }
+
+        @CalledByNative("ChromiumCameraInfo")
+        private int getId() {
+            return mId;
+        }
+
+        @CalledByNative("ChromiumCameraInfo")
+        private String getDeviceName() {
+            return  "camera " + mId + ", facing " +
+                    (mCameraInfo.facing ==
+                     Camera.CameraInfo.CAMERA_FACING_FRONT ? "front" : "back");
+        }
+
+        @CalledByNative("ChromiumCameraInfo")
+        private int getOrientation() {
+            return mCameraInfo.orientation;
+        }
+    }
+
     private native void nativeOnFrameAvailable(
             int nativeVideoCaptureDeviceAndroid,
             byte[] data,
diff --git a/media/media.gyp b/media/media.gyp
index 04e7ae4..5fc573a 100644
--- a/media/media.gyp
+++ b/media/media.gyp
@@ -1426,21 +1426,8 @@
           'includes': [ '../build/jni_generator.gypi' ],
         },
         {
-          'target_name': 'camera_jni_headers',
-          'type': 'none',
-          'variables': {
-            'jni_gen_package': 'media',
-            'input_java_class': 'android/hardware/Camera.class',
-            'input_jar_file': '<(android_sdk)/android.jar',
-          },
-          'includes': [ '../build/jar_file_jni_generator.gypi' ],
-        },
-        {
           'target_name': 'video_capture_android_jni_headers',
           'type': 'none',
-          'dependencies': [
-            'camera_jni_headers',
-          ],
           'sources': [
             'base/android/java/src/org/chromium/media/VideoCapture.java',
           ],
diff --git a/media/video/capture/android/video_capture_device_android.cc b/media/video/capture/android/video_capture_device_android.cc
index 4cd8e4e..d837b24 100644
--- a/media/video/capture/android/video_capture_device_android.cc
+++ b/media/video/capture/android/video_capture_device_android.cc
@@ -7,10 +7,10 @@
 #include <string>
 
 #include "base/android/jni_android.h"
+#include "base/android/jni_string.h"
 #include "base/android/scoped_java_ref.h"
 #include "base/string_number_conversions.h"
 #include "base/stringprintf.h"
-#include "jni/Camera_jni.h"
 #include "jni/VideoCapture_jni.h"
 #include "media/base/video_util.h"
 
@@ -42,53 +42,28 @@ void VideoCaptureDevice::GetDeviceNames(Names* device_names) {
 
   JNIEnv* env = AttachCurrentThread();
 
-  int num_cameras = JNI_Camera::Java_Camera_getNumberOfCameras(env);
+  int num_cameras = Java_ChromiumCameraInfo_getNumberOfCameras(env);
   DVLOG(1) << "VideoCaptureDevice::GetDeviceNames: num_cameras=" << num_cameras;
   if (num_cameras <= 0)
     return;
 
-  // TODO(wjia): switch to using same approach as Camera when
-  // jar_file_jni_generator.gypi supports system inner classes.
-  std::string camera_info_string("android/hardware/Camera$CameraInfo");
-
-  ScopedJavaLocalRef<jclass> camera_info_class(
-      GetClass(env, camera_info_string.c_str()));
-  jmethodID constructor = MethodID::Get<MethodID::TYPE_INSTANCE>(
-      env, camera_info_class.obj(), "<init>", "()V");
-
-  ScopedJavaLocalRef<jobject> object_camera_info(
-      env, env->NewObject(camera_info_class.obj(), constructor));
-
-  jfieldID field_facing = GetFieldID(env, camera_info_class, "facing", "I");
-  jfieldID field_facing_front = GetStaticFieldID(
-      env, camera_info_class, "CAMERA_FACING_FRONT", "I");
-
   for (int camera_id = num_cameras - 1; camera_id >= 0; --camera_id) {
-    JNI_Camera::Java_Camera_getCameraInfo(
-        env, camera_id, object_camera_info.obj());
+    ScopedJavaLocalRef<jobject> ci =
+        Java_ChromiumCameraInfo_getAt(env, camera_id);
 
     Name name;
-    name.unique_id = StringPrintf("%d", camera_id);
-    std::string facing_string;
-    if (env->GetIntField(object_camera_info.obj(), field_facing) ==
-        env->GetStaticIntField(camera_info_class.obj(), field_facing_front)) {
-      facing_string = "front";
-    } else {
-      facing_string = "back";
-    }
-    name.device_name = StringPrintf(
-        "camera %d, facing %s", camera_id, facing_string.c_str());
+    name.unique_id = StringPrintf(
+        "%d", Java_ChromiumCameraInfo_getId(env, ci.obj()));
+    name.device_name = base::android::ConvertJavaStringToUTF8(
+        Java_ChromiumCameraInfo_getDeviceName(env, ci.obj()));
     device_names->push_back(name);
-    jfieldID field_orientation = GetFieldID(
-        env, camera_info_class, "orientation", "I");
-    jint orientation = env->GetIntField(object_camera_info.obj(),
-                                        field_orientation);
+
     DVLOG(1) << "VideoCaptureDevice::GetDeviceNames: camera device_name="
              << name.device_name
              << ", unique_id="
              << name.unique_id
              << ", orientation "
-             << orientation;
+             << Java_ChromiumCameraInfo_getOrientation(env, ci.obj());
   }
 }
 
@@ -108,7 +83,7 @@ VideoCaptureDevice* VideoCaptureDeviceAndroid::Create(const Name& device_name) {
 
 // static
 bool VideoCaptureDeviceAndroid::RegisterVideoCaptureDevice(JNIEnv* env) {
-  return RegisterNativesImpl(env) && JNI_Camera::RegisterNativesImpl(env);
+  return RegisterNativesImpl(env);
 }
 
 VideoCaptureDeviceAndroid::VideoCaptureDeviceAndroid(const Name& device_name)