VideoCapture: Remove deep frame copy in the border to libJingle

media/base/video_frame.h

Index: media/base/video_frame.h
diff --git a/media/base/video_frame.h b/media/base/video_frame.h
index 928550cbd0724b2624f164970d8763e81f9207e6..1eb974d1928f58709198f5a91a5f1a71e465f7ef 100644
--- a/media/base/video_frame.h
+++ b/media/base/video_frame.h
@@ -265,7 +265,13 @@ class MEDIA_EXPORT VideoFrame : public base::RefCountedThreadSafe<VideoFrame> {
 
   // Returns pointer to the buffer for a given plane. The memory is owned by
   // VideoFrame object and must not be freed by the caller.
-  uint8* data(size_t plane) const;
+  const uint8* data(size_t plane) const;
+  uint8* data(size_t plane);

[scherkus (not reviewing), 2014/10/20 19:30:36]

do we need both the const and non-const versions?

could we get away with just having the uint8* version, or does that break
things?

AFAICT webrtc_video_capturer_adapter.cc should still compile upgrading a uint8*
-> const uint8*

[magjed_chromium, 2014/10/22 15:16:39]

Everything will compile and work using the old declaration:
uint8* data(size_t plane) const
but returning a non-const pointer to internal data from a const method goes
against the style guide. So that's the reason for having two methods: const
method returning const, and non-const method returning non-const.
Reference: 
http://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Use_of_const
"Declare methods to be const whenever possible. Accessors should almost always
be const. Other methods should be const if they do not modify any data members,
do not call any non-const methods, and do not return a non-const pointer or
non-const reference to a data member."

+
+  // Returns pointer to the visible region specified by visible_rect(). The
+  // memory is owned by VideoFrame object and must not be freed by the caller.
+  const uint8* visible_data(size_t plane) const;

[scherkus (not reviewing), 2014/10/20 19:30:36]

ditto

[magjed_chromium, 2014/10/22 15:16:39]

See above.

+  uint8* visible_data(size_t plane);
 
   // Returns the mailbox holder of the native texture wrapped by this frame.
   // Only valid to call if this is a NATIVE_TEXTURE frame. Before using the