Fix screen mirroring on Chrome OS (ReflectorTexture partial swap)

content/browser/compositor/reflector_texture.cc

Index: content/browser/compositor/reflector_texture.cc
diff --git a/content/browser/compositor/reflector_texture.cc b/content/browser/compositor/reflector_texture.cc
index 7db8c87cc8cacfc076fdd535c93333a8d252dbf8..7f32fa17123a372492499239c2d4852942098fbb 100644
--- a/content/browser/compositor/reflector_texture.cc
+++ b/content/browser/compositor/reflector_texture.cc
@@ -31,6 +31,7 @@ ReflectorTexture::~ReflectorTexture() {
 }
 
 void ReflectorTexture::CopyTextureFullImage(const gfx::Size& size) {
+  is_texture_defined_ = true;
   gl_helper_->CopyTextureFullImage(texture_id_, size);
   // Insert a barrier to make the copy show up in the mirroring compositor's
   // mailbox. Since the the compositor contexts and the
@@ -41,6 +42,7 @@ void ReflectorTexture::CopyTextureFullImage(const gfx::Size& size) {
 }
 
 void ReflectorTexture::CopyTextureSubImage(const gfx::Rect& rect) {
+  DCHECK(is_texture_defined_);
   gl_helper_->CopyTextureSubImage(texture_id_, rect);
   // Insert a barrier for the same reason above.
   gl_helper_->InsertOrderingBarrier();