Aura: PostSubBuffer implementation for --ui-use-gpu-process

content/common/gpu/image_transport_surface.cc

Index: content/common/gpu/image_transport_surface.cc
diff --git a/content/common/gpu/image_transport_surface.cc b/content/common/gpu/image_transport_surface.cc
index 2f12e7bb444705e2b25bcf0692c82d9da6c6c1e5..3160abb7fb4fc804bb76f0b65272c95f79b0034c 100644
--- a/content/common/gpu/image_transport_surface.cc
+++ b/content/common/gpu/image_transport_surface.cc
@@ -22,6 +22,42 @@ ImageTransportSurface::ImageTransportSurface() {
 ImageTransportSurface::~ImageTransportSurface() {
 }
 
+void ImageTransportSurface::GetRegionsToCopy(
+    const gfx::Rect& previous_damage_rect,
+    const gfx::Rect& new_damage_rect,
+    std::vector<gfx::Rect>* regions) {
+  gfx::Rect intersection = previous_damage_rect.Intersect(new_damage_rect);
+
+  if (intersection.IsEmpty()) {
+    regions->push_back(previous_damage_rect);
+    return;
+  }
+
+  // Top (above the intersection).
+  regions->push_back(gfx::Rect(previous_damage_rect.x(),
+      previous_damage_rect.y(),
+      previous_damage_rect.width(),
+      intersection.y() - previous_damage_rect.y()));
+
+  // Left (of the intersection).
+  regions->push_back(gfx::Rect(previous_damage_rect.x(),
+      intersection.y(),
+      intersection.x() - previous_damage_rect.x(),
+      intersection.height()));
+
+  // Right (of the intersection).
+  regions->push_back(gfx::Rect(intersection.right(),
+      intersection.y(),
+      previous_damage_rect.right() - intersection.right(),
+      intersection.height()));
+
+  // Bottom (below the intersection).
+  regions->push_back(gfx::Rect(previous_damage_rect.x(),
+      intersection.bottom(),
+      previous_damage_rect.width(),
+      previous_damage_rect.bottom() - intersection.bottom()));
+}
+
 ImageTransportHelper::ImageTransportHelper(ImageTransportSurface* surface,
                                            GpuChannelManager* manager,
                                            GpuCommandBufferStub* stub,