Add check for null pointer

third_party/WebKit/Source/modules/encryptedmedia/ContentDecryptionModuleResultPromise.cpp

Index: third_party/WebKit/Source/modules/encryptedmedia/ContentDecryptionModuleResultPromise.cpp
diff --git a/third_party/WebKit/Source/modules/encryptedmedia/ContentDecryptionModuleResultPromise.cpp b/third_party/WebKit/Source/modules/encryptedmedia/ContentDecryptionModuleResultPromise.cpp
index 728f35442fb0954f16fb04d52a231c72b576ab1c..c65194b436d3af6e2f5e610de4ec11bc95a8db51 100644
--- a/third_party/WebKit/Source/modules/encryptedmedia/ContentDecryptionModuleResultPromise.cpp
+++ b/third_party/WebKit/Source/modules/encryptedmedia/ContentDecryptionModuleResultPromise.cpp
@@ -96,7 +96,9 @@ void ContentDecryptionModuleResultPromise::reject(ExceptionCode code, const Stri
     // already posted that need to happen only after the promise is resolved.)
     // TODO(jrummell): Make resolving a promise asynchronous as well (including
     // making sure events still happen after the promise is resolved).
-    getExecutionContext()->postTask(BLINK_FROM_HERE, createSameThreadTask(&ContentDecryptionModuleResultPromise::rejectInternal, wrapPersistent(this), code, errorMessage));
+    if (getExecutionContext()) {
+        getExecutionContext()->postTask(BLINK_FROM_HERE, createSameThreadTask(&ContentDecryptionModuleResultPromise::rejectInternal, wrapPersistent(this), code, errorMessage));
+    }
 }
 
 void ContentDecryptionModuleResultPromise::rejectInternal(ExceptionCode code, const String& errorMessage)