Add ContextProvider::InvalidateGrContext to reset GL state in GrContext

cc/output/context_provider.h

Index: cc/output/context_provider.h
diff --git a/cc/output/context_provider.h b/cc/output/context_provider.h
index 71d06bd7591d22f180f7a395b5be412d733b03bb..dfaab4a15b214d6e55d4b7a7e3b743f193be3801 100644
--- a/cc/output/context_provider.h
+++ b/cc/output/context_provider.h
@@ -44,6 +44,10 @@ class ContextProvider : public base::RefCountedThreadSafe<ContextProvider> {
     CC_EXPORT Capabilities();
   };
 
+  // Invalidates the cached OpenGL state in GrContext.
+  // See skia GrContext::resetContext for details.
+  virtual void InvalidateGrContext(uint32_t state) = 0;
+
   // Sets up a lock so this context can be used from multiple threads.
   virtual void SetupLock() = 0;