Add ContextProvider::InvalidateGrContext to reset GL state in GrContext

mojo/cc/context_provider_mojo.cc

Index: mojo/cc/context_provider_mojo.cc
diff --git a/mojo/cc/context_provider_mojo.cc b/mojo/cc/context_provider_mojo.cc
index aed1712e80a3f22d90e3990af8946306798dc6db..dff93621adabf4f3f28232445d779a023d049b36 100644
--- a/mojo/cc/context_provider_mojo.cc
+++ b/mojo/cc/context_provider_mojo.cc
@@ -39,6 +39,9 @@ gpu::ContextSupport* ContextProviderMojo::ContextSupport() {
 
 class GrContext* ContextProviderMojo::GrContext() { return NULL; }
 
+void ContextProviderMojo::InvalidateGrContext(uint32_t state) {
+}
+
 cc::ContextProvider::Capabilities ContextProviderMojo::ContextCapabilities() {
   return capabilities_;
 }