Add support for scaling textures in AndroidVideoCapturer.

The idea is to also reuse AndroidTextureBuffer::CropAndScale when scaling in the encoder.

BUG=webrtc:4993
R=magjed@webrtc.org

Review URL: https://codereview.webrtc.org/1471333003 .

Cr-Commit-Position: refs/heads/master@{#10802}

talk/app/webrtc/java/android/org/webrtc/VideoCapturerAndroid.java

@@ -300,6 +300,8 @@ public class VideoCapturerAndroid extends VideoCapturer implements
 
   // Requests a new output format from the video capturer. Captured frames
   // by the camera will be scaled/or dropped by the video capturer.
+  // It does not matter if width and height are flipped. I.E, |width| = 640, |height| = 480 produce
+  // the same result as |width| = 480, |height| = 640.
   // TODO(magjed/perkj): Document what this function does. Change name?
   public void onOutputFormatRequest(final int width, final int height, final int framerate) {
     cameraThreadHandler.post(new Runnable() {

talk/app/webrtc/java/jni/native_handle_impl.cc

@@ -28,9 +28,17 @@
 #include "talk/app/webrtc/java/jni/native_handle_impl.h"
 
 #include "webrtc/base/checks.h"
+#include "webrtc/base/bind.h"
+
+using rtc::scoped_refptr;
+using webrtc::NativeHandleBuffer;
 
 namespace webrtc_jni {
 
+namespace {
+void ScaledFrameNotInUse(scoped_refptr<NativeHandleBuffer> original) {}
+}  // anonymous namespace
+
 NativeHandleImpl::NativeHandleImpl(JNIEnv* jni,
                                    jint j_oes_texture_id,
                                    jfloatArray j_transform_matrix)
@@ -64,4 +72,22 @@ AndroidTextureBuffer::NativeToI420Buffer() {
   return nullptr;
 }
 
+rtc::scoped_refptr<AndroidTextureBuffer> AndroidTextureBuffer::CropAndScale(
+    int cropped_input_width,
+    int cropped_input_height,
+    int dst_widht,
+    int dst_height) {
+  // TODO(perkj) Implement cropping.
+  RTC_CHECK_EQ(cropped_input_width, width_);
+  RTC_CHECK_EQ(cropped_input_height, height_);
+
+  // Here we use Bind magic to add a reference count to |this| until the newly
+  // created AndroidTextureBuffer is destructed. ScaledFrameNotInUse will be
+  // called that happens and when it finishes, the reference count to |this|
+  // will be decreased by one.
+  return new rtc::RefCountedObject<AndroidTextureBuffer>(
+      dst_widht, dst_height, native_handle_,
+      rtc::Bind(&ScaledFrameNotInUse, this));
+}
+
 }  // namespace webrtc_jni

talk/app/webrtc/java/jni/native_handle_impl.h

@@ -54,6 +54,12 @@ class AndroidTextureBuffer : public webrtc::NativeHandleBuffer {
   ~AndroidTextureBuffer();
   rtc::scoped_refptr<VideoFrameBuffer> NativeToI420Buffer() override;
 
+  rtc::scoped_refptr<AndroidTextureBuffer> CropAndScale(
+      int cropped_input_width,
+      int cropped_input_height,
+      int dst_widht,
+      int dst_height);
+
  private:
   NativeHandleImpl native_handle_;
   rtc::Callback0<void> no_longer_used_cb_;