Unhide the android.media.[Media]DataSource interface.

This allows apps to implement MediaDataSource, which is modeled on
stagefright's DataSource, to supply media data to the framework. This
was already implemented for MediaExtractor, but it was renamed from
DataSource.

MediaExtractor, MediaPlayer and MediaMetadataRetriever each have a new
overload: #setDataSource(android.media.MediaDataSource)

Only NuPlayer supports this new data source.

The change introduces:
 * IDataSource:        The binder interface for DataSource.
 * JMediaDataSource:   The native counterpart to the java interface. It
                       implements IDataSource.
 * CallbackDataSource: A stagefright DataSource that wraps an IDataSource.

Change-Id: I6d9c1167b4a7384c469b1e928f31791a7ebed716
diff --git a/media/jni/android_media_MediaExtractor.cpp b/media/jni/android_media_MediaExtractor.cpp
index c0795b6..b6b7a80 100644
--- a/media/jni/android_media_MediaExtractor.cpp
+++ b/media/jni/android_media_MediaExtractor.cpp
@@ -25,6 +25,7 @@
 #include "android_runtime/Log.h"
 #include "jni.h"
 #include "JNIHelp.h"
+#include "android_media_MediaDataSource.h"
 
 #include <media/IMediaHTTPService.h>
 #include <media/hardware/CryptoAPI.h>
@@ -50,74 +51,6 @@
 
 static fields_t gFields;
 
-class JavaDataSourceBridge : public DataSource {
-    jmethodID mReadMethod;
-    jmethodID mGetSizeMethod;
-    jmethodID mCloseMethod;
-    jobject   mDataSource;
- public:
-    JavaDataSourceBridge(JNIEnv *env, jobject source) {
-        mDataSource = env->NewGlobalRef(source);
-
-        jclass datasourceclass = env->GetObjectClass(mDataSource);
-        CHECK(datasourceclass != NULL);
-
-        mReadMethod = env->GetMethodID(datasourceclass, "readAt", "(J[BI)I");
-        CHECK(mReadMethod != NULL);
-
-        mGetSizeMethod = env->GetMethodID(datasourceclass, "getSize", "()J");
-        CHECK(mGetSizeMethod != NULL);
-
-        mCloseMethod = env->GetMethodID(datasourceclass, "close", "()V");
-        CHECK(mCloseMethod != NULL);
-    }
-
-    ~JavaDataSourceBridge() {
-        JNIEnv *env = AndroidRuntime::getJNIEnv();
-        env->CallVoidMethod(mDataSource, mCloseMethod);
-        env->DeleteGlobalRef(mDataSource);
-    }
-
-    virtual status_t initCheck() const {
-        return OK;
-    }
-
-    virtual ssize_t readAt(off64_t offset, void* buffer, size_t size) {
-        JNIEnv *env = AndroidRuntime::getJNIEnv();
-
-        // XXX could optimize this by reusing the same array
-        jbyteArray byteArrayObj = env->NewByteArray(size);
-        env->DeleteLocalRef(env->GetObjectClass(mDataSource));
-        env->DeleteLocalRef(env->GetObjectClass(byteArrayObj));
-        ssize_t numread = env->CallIntMethod(mDataSource, mReadMethod, offset, byteArrayObj, (jint)size);
-        env->GetByteArrayRegion(byteArrayObj, 0, size, (jbyte*) buffer);
-        env->DeleteLocalRef(byteArrayObj);
-        if (env->ExceptionCheck()) {
-            ALOGW("Exception occurred while reading %zu at %lld", size, (long long)offset);
-            LOGW_EX(env);
-            env->ExceptionClear();
-            return -1;
-        }
-        return numread;
-    }
-
-    virtual status_t getSize(off64_t *size) {
-        JNIEnv *env = AndroidRuntime::getJNIEnv();
-
-        CHECK(size != NULL);
-
-        int64_t len = env->CallLongMethod(mDataSource, mGetSizeMethod);
-        if (len < 0) {
-            *size = ERROR_UNSUPPORTED;
-        } else {
-            *size = len;
-        }
-        return OK;
-    }
-};
-
-////////////////////////////////////////////////////////////////////////////////
-
 JMediaExtractor::JMediaExtractor(JNIEnv *env, jobject thiz)
     : mClass(NULL),
       mObject(NULL) {
@@ -777,7 +710,8 @@
         return;
     }
 
-    sp<JavaDataSourceBridge> bridge = new JavaDataSourceBridge(env, callbackObj);
+    sp<DataSource> bridge =
+        DataSource::CreateFromIDataSource(new JMediaDataSource(env, callbackObj));
     status_t err = extractor->setDataSource(bridge);
 
     if (err != OK) {
@@ -881,7 +815,7 @@
     { "setDataSource", "(Ljava/io/FileDescriptor;JJ)V",
       (void *)android_media_MediaExtractor_setDataSourceFd },
 
-    { "setDataSource", "(Landroid/media/DataSource;)V",
+    { "setDataSource", "(Landroid/media/MediaDataSource;)V",
       (void *)android_media_MediaExtractor_setDataSourceCallback },
 
     { "getCachedDuration", "()J",