Revert of [devtools] Support different encodings for Page.CaptureScreenshot.

ui/gfx/image/image_util.h

Index: ui/gfx/image/image_util.h
diff --git a/ui/gfx/image/image_util.h b/ui/gfx/image/image_util.h
index cee54a351f4e93f87be3bace6a65776dfcd9c114..8f17c368a8cada1d3456f17fc1b53b23c9eef03f 100644
--- a/ui/gfx/image/image_util.h
+++ b/ui/gfx/image/image_util.h
@@ -33,10 +33,6 @@
                                            int quality,
                                            std::vector<unsigned char>* dst);
 
-bool JPEG1xEncodedDataFromSkiaRepresentation(const Image& image,
-                                             int quality,
-                                             std::vector<unsigned char>* dst);
-
 // Computes the width of any nearly-transparent regions at the sides of the
 // image and returns them in |left| and |right|.  This checks each column of
 // pixels from the outsides in, looking for anything with alpha above a