Cherry-pick: Fix typo in media context restore

Clean cherry-pick of chromium
crrev.com/bfb71fc03179ac0d88c6b6d188915cf0dd363071

BUG: 17354106

Review URL: https://codereview.chromium.org/581703002

Change-Id: I62059284e4ab126dbb3bfde32b248e7fb12bd842
Cr-Commit-Position: refs/heads/master@{#295295}
diff --git a/content/renderer/media/android/stream_texture_factory_synchronous_impl.cc b/content/renderer/media/android/stream_texture_factory_synchronous_impl.cc
index fb2bdf2..2beaf3b 100644
--- a/content/renderer/media/android/stream_texture_factory_synchronous_impl.cc
+++ b/content/renderer/media/android/stream_texture_factory_synchronous_impl.cc
@@ -228,7 +228,7 @@
   DCHECK_EQ(observer_, obs);
   observer_ = NULL;
   if (context_provider_)
-    context_provider_->AddObserver(obs);
+    context_provider_->RemoveObserver(obs);
 }
 
 }  // namespace content