cc: Add ResourceId validation checks at the time of AppendQuads.

cc/resources/resource_provider.cc

Index: cc/resources/resource_provider.cc
diff --git a/cc/resources/resource_provider.cc b/cc/resources/resource_provider.cc
index f31cfd4da34e776878b87574f37a281741467f94..1307897ee2e7e4f5484fb153b34a58f8144b665d 100644
--- a/cc/resources/resource_provider.cc
+++ b/cc/resources/resource_provider.cc
@@ -2134,6 +2134,13 @@ GLint ResourceProvider::GetActiveTextureUnit(GLES2Interface* gl) {
   return active_unit;
 }
 
+void ResourceProvider::ValidateResource(ResourceId id) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  CHECK(id);
+  ResourceMap::iterator it = resources_.find(id);
+  CHECK(it != resources_.end());

[piman, 2015/04/07 00:13:39]

nit: all that is essentially (void)GetResource(id);

[danakj, 2015/04/07 00:15:00]

Ya I copied it from there. Heh. My random thought was that I would go back and
remove the CHECK(id) in GetResource, but maybe we'd wanna keep this function
around behind DCHECK_IS_ON() and it'd be nice to keep here. I will add a TODO on
the CHECK in GetResource.

+}
+
 GLES2Interface* ResourceProvider::ContextGL() const {
   ContextProvider* context_provider = output_surface_->context_provider();
   return context_provider ? context_provider->ContextGL() : NULL;