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..a6b2bd336fad663610487fe79c7e5b8dc4f3f880 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
@@ -195,6 +199,24 @@ class CONTENT_EXPORT RenderWidgetHost : public IPC::Sender {
   virtual bool CopyFromBackingStoreToCGContext(const CGRect& dest_rect,
                                                CGContextRef target) = 0;
 #endif
+  // Returns true if CopyFromBackingStoreToVideoFrame is possible on the current
+  // backing store. Depends on platform support and compositor state. Callers
+  // should check this before each call to CopyFromBackingStoreToVideoFrame().
+  virtual bool CanCopyToVideoFrame() const = 0;
+  // Copies a given subset of the backing store into a YV12 VideoFrame, and pass
+  // it to the callback. The resulting VideoFrame will always be exactly
+  // |dst_size|. If |src_rect| does not match |dst_size|, the copied content
+  // will be scaled and letterboxed with black borders. Callbacks are permitted
+  // to take a refcount on the resulting VideoFrame for further processing on
+  // other threads.
+  //
+  // CopyFromBackingStoreToVideoFrame is not always possible. Callers should
+  // 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 gfx::Size& dst_size,
+      const base::Callback<void(media::VideoFrame*)>& callback) = 0;
 
   // Send a command to the renderer to turn on full accessibility.
   virtual void EnableFullAccessibilityMode() = 0;