cc: Add OutputSurface state snapshots.

components/display_compositor/buffer_queue.cc

Index: components/display_compositor/buffer_queue.cc
diff --git a/components/display_compositor/buffer_queue.cc b/components/display_compositor/buffer_queue.cc
index fafdb406b4feee839d0736a838647d135aa1101e..cad2c921bd500930bc3805614c4fd81288b42fb8 100644
--- a/components/display_compositor/buffer_queue.cc
+++ b/components/display_compositor/buffer_queue.cc
@@ -243,6 +243,24 @@ std::unique_ptr<BufferQueue::AllocatedSurface> BufferQueue::GetNextSurface() {
                                             id, gfx::Rect(size_));
 }
 
+void BufferQueue::ReadbackDisplayedFramebuffer(
+    SkBitmap* bitmap,
+    const base::Callback<void(bool)>& callback) {
+  if (!displayed_surface_) {
+    callback.Run(false);
+    return;
+  }
+  GLuint texture = gl_helper_->CreateTexture();
+  ScopedTextureBinder<GL_TEXTURE_2D> texture_binder(gl_, texture);
+  gl_->CopyTextureCHROMIUM(displayed_surface_->texture, texture, GL_RGBA,
+                           GL_UNSIGNED_BYTE, false, false, false);
+  bitmap->allocN32Pixels(size_.width(), size_.height());
+  gl_helper_->ReadbackTextureAsync(
+      texture, size_, static_cast<unsigned char*>(bitmap->getPixels()),
+      kRGBA_8888_SkColorType, callback);
+  gl_helper_->DeleteTexture(texture);
+}
+
 BufferQueue::AllocatedSurface::AllocatedSurface(
     BufferQueue* buffer_queue,
     std::unique_ptr<gfx::GpuMemoryBuffer> buffer,