media: Reject pending CDM promise during destruction.

third_party/WebKit/public/platform/WebContentDecryptionModuleResult.h

Index: third_party/WebKit/public/platform/WebContentDecryptionModuleResult.h
diff --git a/third_party/WebKit/public/platform/WebContentDecryptionModuleResult.h b/third_party/WebKit/public/platform/WebContentDecryptionModuleResult.h
index 9d16de997517112ef96501044288607c8f9e779e..52ba45424e3d5d2098f0568e2ae309469581b867 100644
--- a/third_party/WebKit/public/platform/WebContentDecryptionModuleResult.h
+++ b/third_party/WebKit/public/platform/WebContentDecryptionModuleResult.h
@@ -45,6 +45,9 @@ public:
         return *this;
     }
 
+    // Returns whether the operation has been completed (success or failure).
+    BLINK_PLATFORM_EXPORT bool isCompleted();

[pfeldman, 2016/03/01 18:34:31]

It seems counter-intuitive that you query for completion here, while you report
completion below. Which side is in control? Would it make sense to file
completion upon client destruction instead?

[xhwang, 2016/03/01 18:51:06]

This is exactly what this CL is doing.

isCompleted() is added only for a sanity dcheck (see the change in
media/blink/cdm_result_promise.h). If you feel that check is redundant, I can
totally drop this change here.

+
     // Called when the CDM completes an operation and has no additional data to
     // pass back.
     BLINK_PLATFORM_EXPORT void complete();