Tab Capture: Backing store readbacks to YV12 VideoFrames.

Goal here is performance; in tab capture there are
significant benefits to doing the readback as YV12:
it's less data to copy back, and it's cheap to do
on the GPU.

VideoFrame is used because it's the most capable YV12
container.

[render_widget_host.h] 
Add a new flavor of CopyFromBackingStore, called 
CopyFromBackingStoreToVideoFrame. The semantics are 
slightly different from the RGBA copy in ways that are 
video-appropriate: aspect ratio is preserved via 
letterboxing, meaning the output is returned at the target's
allocated size, no matter what (whereas CopyFromBackingStore
returns whatever it wants, treating |dst_size| as a hint).

Callers may only call CopyFromBackingStoreToVideoFrame
after checking the result of CanCopyToVideoFrame(). 
Support is only on Windows now, and only while accelerated
compositing is active. But the interface defined
here should make it possible to implement VideoFrame
readbacks on other platforms without having to touch
the callers.

[video_capture_controller.h]
Amend the interface to allow a VideoFrame to
be passed in, as an alternative to void*.
The buffer-based interface was inadequate for
our needs since stride was not handled. Using
VideoFrame allows strides to be accomodated,
and paves the way for the interface to
pre-reserve the VideoFrames.

[web_contents_video_capture_device.cc]
Start using CopyFromBackingStoreToVideoFrame. Handling
both copy flavors requires a bifurcation of much
of the processing pipeline. When dealing with a VideoFrame,
the Render stage can is bypassed completely.

[accelerated_surface_win.h]
Implementation of VideoFrame YV12 readback, using
AcceleratedSurfaceTransformer's d3d-accelerated routines.

BUG=161537

Review URL: https://chromiumcodereview.appspot.com/12090109

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@181785 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 16 insertions, 11 deletions

diff --git a/ui/surface/accelerated_surface_transformer_win.cc b/ui/surface/accelerated_surface_transformer_win.cc
index 694f169..30fd1af 100644
--- a/ui/surface/accelerated_surface_transformer_win.cc
+++ b/ui/surface/accelerated_surface_transformer_win.cc
@@ -69,8 +69,7 @@ class ScopedRenderTargetRestorer {
 // by repeating downsampling of the image of |src_subrect| by a factor no more
 // than 2.
 int GetResampleCount(const gfx::Rect& src_subrect,
-                     const gfx::Size& dst_size,
-                     const gfx::Size& back_buffer_size) {
+                     const gfx::Size& dst_size) {
   // At least one copy is required, since the back buffer itself is not
   // lockable.
   int min_resample_count = 1;
@@ -319,17 +318,17 @@ void AcceleratedSurfaceTransformer::DrawScreenAlignedQuad(
 bool AcceleratedSurfaceTransformer::ResizeBilinear(
     IDirect3DSurface9* src_surface,
     const gfx::Rect& src_subrect,
-    IDirect3DSurface9* dst_surface) {
-  gfx::Size src_size = d3d_utils::GetSize(src_surface);
-  gfx::Size dst_size = d3d_utils::GetSize(dst_surface);
+    IDirect3DSurface9* dst_surface,
+    const gfx::Rect& dst_rect) {
+  gfx::Size src_size = src_subrect.size();
+  gfx::Size dst_size = dst_rect.size();
 
   if (src_size.IsEmpty() || dst_size.IsEmpty())
     return false;
 
   HRESULT hr = S_OK;
   // Set up intermediate buffers needed for downsampling.
-  const int resample_count =
-      GetResampleCount(src_subrect, dst_size, src_size);
+  const int resample_count = GetResampleCount(src_subrect, dst_size);
   base::win::ScopedComPtr<IDirect3DSurface9> temp_buffer[2];
   const gfx::Size half_size =
       GetHalfSizeNoLessThan(src_subrect.size(), dst_size);
@@ -360,10 +359,16 @@ bool AcceleratedSurfaceTransformer::ResizeBilinear(
     TRACE_EVENT0("gpu", "StretchRect");
     IDirect3DSurface9* read_buffer =
         (i == 0) ? src_surface : temp_buffer[read_buffer_index];
-    IDirect3DSurface9* write_buffer =
-        (i == resample_count - 1) ? dst_surface :
-                                    temp_buffer[write_buffer_index];
-    RECT write_rect = gfx::Rect(write_size).ToRECT();
+    IDirect3DSurface9* write_buffer;
+    RECT write_rect;
+    if (i == resample_count - 1) {
+      write_buffer = dst_surface;
+      write_rect = dst_rect.ToRECT();
+    } else {
+      write_buffer = temp_buffer[write_buffer_index];
+      write_rect = gfx::Rect(write_size).ToRECT();
+    }
+
     hr = device()->StretchRect(read_buffer,
                                &read_rect,
                                write_buffer,