Tab Capture: Backing store readbacks to YV12 VideoFrames.

content/public/browser/render_widget_host.h

Index: content/public/browser/render_widget_host.h
diff --git a/content/public/browser/render_widget_host.h b/content/public/browser/render_widget_host.h
index a0e8d8a70d3754cab16206f905e10bd48e5741dd..e79f01270b3d0285e9d55c414c6d9beeba15dadf 100644
--- a/content/public/browser/render_widget_host.h
+++ b/content/public/browser/render_widget_host.h
@@ -28,6 +28,10 @@ namespace gfx {
 class Rect;
 }
 
+namespace media {
+class VideoFrame;
+}
+
 namespace content {
 
 class RenderProcessHost;
@@ -168,8 +172,8 @@ class CONTENT_EXPORT RenderWidgetHost : public IPC::Sender {
   // contents, but e.g. in the omnibox.
   virtual void SetActive(bool active) = 0;
 
-  // Copies the given subset of the backing store, and passes the result as a
-  // bitmap to a callback.
+  // Copies the given subset of the backing store, and passes the result as an
+  // ARGB bitmap to a callback.
   //
   // If |src_rect| is empty, the whole contents is copied. If non empty
   // |accelerated_dst_size| is given and accelerated compositing is active, the
@@ -196,6 +200,24 @@ class CONTENT_EXPORT RenderWidgetHost : public IPC::Sender {
                                                CGContextRef target) = 0;
 #endif
 
+  // Returns true if CopyFromBackingStoreToVideoFrame() is possible on the
+  // current backing store. Depends on platform support and compositor state.
+  virtual bool CanCopyToVideoFrame() const = 0;
+
+  // Copies a given subset of the backing store into a YV12 VideoFrame, and
+  // invokes a callback with a success/fail parameter. |target| must contain an
+  // allocated, YV12 video frame of the intended size. If |src_rect| does not
+  // match the |target|'s size, the copied content will be scaled and
+  // letterboxed with black borders. The copy may happen asynchronously.
+  //
+  // CopyFromBackingStoreToVideoFrame() is not always possible. Callers must
+  // check the return value of CanCopyToVideoFrame(), and if false, fall back to
+  // a different method such as CopyFromBackingStore().
+  virtual void CopyFromBackingStoreToVideoFrame(
+      const gfx::Rect& src_rect,
+      const scoped_refptr<media::VideoFrame>& target,
+      const base::Callback<void(bool)>& callback) = 0;
+
   // Send a command to the renderer to turn on full accessibility.
   virtual void EnableFullAccessibilityMode() = 0;