Delete unused and almost unused frame-related methods.

webrtc::VideoFrame::set_video_frame_buffer
webrtc::VideoFrame::ConvertNativeToI420Frame

cricket::WebRtcVideoFrame::InitToBlack

VideoFrameBuffer::data
VideoFrameBuffer::stride
VideoFrameBuffer::MutableData

TBR=tkchin@webrtc.org # Refactoring affecting RTCVideoFrame
BUG=webrtc:5682

Review-Url: https://codereview.webrtc.org/2065733003
Cr-Commit-Position: refs/heads/master@{#13183}
diff --git a/webrtc/api/java/jni/androidmediadecoder_jni.cc b/webrtc/api/java/jni/androidmediadecoder_jni.cc
index 3793756..2ec222f 100644
--- a/webrtc/api/java/jni/androidmediadecoder_jni.cc
+++ b/webrtc/api/java/jni/androidmediadecoder_jni.cc
@@ -794,12 +794,12 @@
       libyuv::I420Copy(y_ptr, stride,
                        u_ptr, uv_stride,
                        v_ptr, uv_stride,
-                       frame_buffer->MutableData(webrtc::kYPlane),
-                       frame_buffer->stride(webrtc::kYPlane),
-                       frame_buffer->MutableData(webrtc::kUPlane),
-                       frame_buffer->stride(webrtc::kUPlane),
-                       frame_buffer->MutableData(webrtc::kVPlane),
-                       frame_buffer->stride(webrtc::kVPlane),
+                       frame_buffer->MutableDataY(),
+                       frame_buffer->StrideY(),
+                       frame_buffer->MutableDataU(),
+                       frame_buffer->StrideU(),
+                       frame_buffer->MutableDataV(),
+                       frame_buffer->StrideV(),
                        width, height);
     } else {
       // All other supported formats are nv12.
@@ -808,12 +808,12 @@
       libyuv::NV12ToI420(
           y_ptr, stride,
           uv_ptr, stride,
-          frame_buffer->MutableData(webrtc::kYPlane),
-          frame_buffer->stride(webrtc::kYPlane),
-          frame_buffer->MutableData(webrtc::kUPlane),
-          frame_buffer->stride(webrtc::kUPlane),
-          frame_buffer->MutableData(webrtc::kVPlane),
-          frame_buffer->stride(webrtc::kVPlane),
+          frame_buffer->MutableDataY(),
+          frame_buffer->StrideY(),
+          frame_buffer->MutableDataU(),
+          frame_buffer->StrideU(),
+          frame_buffer->MutableDataV(),
+          frame_buffer->StrideV(),
           width, height);
     }
     // Return output byte buffer back to codec.