Test abandoning GL context in dm/nanobench.

Rename GrContext::contextDestroyed to GrContext::abandonContext.

Remove GrContext::resetContext.

R=robertphillips@google.com

Author: bsalomon@google.com

Review URL: https://codereview.chromium.org/422903002
diff --git a/src/gpu/GrContext.cpp b/src/gpu/GrContext.cpp
index c171446..6a35ed9 100755
--- a/src/gpu/GrContext.cpp
+++ b/src/gpu/GrContext.cpp
@@ -175,12 +175,7 @@
     fDrawState->unref();
 }
 
-void GrContext::contextLost() {
-    this->contextDestroyed();
-    this->setupDrawBuffer();
-}
-
-void GrContext::contextDestroyed() {
+void GrContext::abandonContext() {
     // abandon first to so destructors
     // don't try to free the resources in the API.
     fGpu->abandonResources();