Add a frame generator that allows scrolling images

webrtc/test/frame_generator.h

Index: webrtc/test/frame_generator.h
diff --git a/webrtc/test/frame_generator.h b/webrtc/test/frame_generator.h
index 03afaccc3067765e24b7e6bc9fb2921e7a558620..7f20c749e8eea9b920ce8b0afde26445eaa10499 100644
--- a/webrtc/test/frame_generator.h
+++ b/webrtc/test/frame_generator.h
@@ -17,6 +17,7 @@
 #include "webrtc/video_frame.h"
 
 namespace webrtc {
+class Clock;
 namespace test {
 
 class FrameGenerator {
@@ -38,6 +39,24 @@ class FrameGenerator {
                                            size_t width,
                                            size_t height,
                                            int frame_repeat_count);
+
+  // Creates a frame generator which takes a set of yuv files (wrapping a
+  // frame generator created by CreateFromYuvFile() above), but outputs frames
+  // that have been cropped to specified resolution: source_width/source_height
+  // is the size of the source images, target_width/target_height is the size of
+  // the cropped output. For each source image read, the cropped viewport will
+  // be scrolled top to bottom/left to right for scroll_tim_ms milliseconds.
+  // After that the image will stay in place for pause_time_ms milliseconds,
+  // and then this will be repeated with the next file from the input set.
+  static FrameGenerator* CreateScrollingInputFromYuvFiles(
+      Clock* clock,
+      std::vector<std::string> filenames,
+      size_t source_width,
+      size_t source_height,
+      size_t target_width,
+      size_t target_height,
+      int64_t scroll_time_ms,
+      int64_t pause_time_ms);
 };
 }  // namespace test
 }  // namespace webrtc