Refactor CdmPromise and related classes

content/renderer/media/cdm_result_promise.h

Index: content/renderer/media/cdm_result_promise.h
diff --git a/content/renderer/media/cdm_result_promise.h b/content/renderer/media/cdm_result_promise.h
index 39bcc0d0e7f1962130019fc5f61a7b22579f2e1d..f987ac4fec5d2d850f40631d152807ee5ad95efa 100644
--- a/content/renderer/media/cdm_result_promise.h
+++ b/content/renderer/media/cdm_result_promise.h
@@ -13,59 +13,52 @@
 
 namespace content {
 
-// Used to convert a WebContentDecryptionModuleResult into a CdmPromise so that
-// it can be passed through Chromium. When CdmPromise::resolve(T) is called,
-// OnResolve(T) will be called and will call the appropriate complete...()
-// method on WebContentDecryptionModuleResult. If CdmPromise::reject() is called
-// instead, WebContentDecryptionModuleResult::completeWithError() is called.
-// If constructed with a |uma_name| (which must be the name of a
-// CdmPromiseResult UMA), CdmResultPromise will report the promise result
-// (success or rejection code).
-template <typename T>
-class CdmResultPromise : public media::CdmPromiseTemplate<T> {
- public:
-  explicit CdmResultPromise(
-      const blink::WebContentDecryptionModuleResult& result);
-  CdmResultPromise(const blink::WebContentDecryptionModuleResult& result,
-                   const std::string& uma_name);
-  virtual ~CdmResultPromise();
-
- protected:
-  // OnResolve() is virtual as it may need special handling in derived classes.
-  virtual void OnResolve(const T& result);
-  void OnReject(media::MediaKeys::Exception exception_code,
-                uint32 system_code,
-                const std::string& error_message);
-
-  blink::WebContentDecryptionModuleResult web_cdm_result_;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(CdmResultPromise);
+// A superset of media::MediaKeys::Exception for UMA reporting. These values
+// should never be changed as it will affect existing reporting, and must match
+// the values for CdmPromiseResult in tools/metrics/histograms/histograms.xml.
+enum ResultCodeForUMA {
+  SUCCESS = 0,
+  NOT_SUPPORTED_ERROR = 1,
+  INVALID_STATE_ERROR = 2,
+  INVALID_ACCESS_ERROR = 3,
+  QUOTA_EXCEEDED_ERROR = 4,
+  UNKNOWN_ERROR = 5,
+  CLIENT_ERROR = 6,
+  OUTPUT_ERROR = 7,
+  NUM_RESULT_CODES
 };
 
-// Specialization for no parameter to resolve().
-template <>
-class CdmResultPromise<void> : public media::CdmPromiseTemplate<void> {
+// Used to convert a WebContentDecryptionModuleResult into a CdmPromiseTemplate
+// so that it can be passed through Chromium. When resolve(T) is called, the
+// appropriate complete...() method on WebContentDecryptionModuleResult will be
+// invoked. If reject() is called instead,
+// WebContentDecryptionModuleResult::completeWithError() is called.
+// If constructed with a |uma_name|, CdmResultPromise will report the promise
+// result (success or rejection code) to UMA.
+template <typename... T>
+class CdmResultPromise : public media::CdmPromiseTemplate<T...> {

[xhwang, 2014/10/03 07:34:21]

Cool!

[jrummell, 2014/10/03 18:58:30]

Acknowledged. I like it too.

  public:
-  explicit CdmResultPromise(
-      const blink::WebContentDecryptionModuleResult& result);
   CdmResultPromise(const blink::WebContentDecryptionModuleResult& result,
                    const std::string& uma_name);
   virtual ~CdmResultPromise();
 
- protected:
-  virtual void OnResolve();
-  void OnReject(media::MediaKeys::Exception exception_code,
-                uint32 system_code,
-                const std::string& error_message);
+  // CdmPromiseTemplate<T> implementation.
+  virtual void resolve(const T&... result) OVERRIDE;
+  virtual void reject(media::MediaKeys::Exception exception_code,
+                      uint32 system_code,
+                      const std::string& error_message) OVERRIDE;
 
+ protected:
   blink::WebContentDecryptionModuleResult web_cdm_result_;
 
  private:

[xhwang, 2014/10/03 07:34:21]

You can have this here:

using media::CdmPromiseTemplate<T...>::PromiseSettled;

so that you don't need the "this->" part in this->PromiseSettled.

[jrummell, 2014/10/03 18:58:30]

Done.

+  // UMA name to report result to.
+  std::string uma_name_;
+
   DISALLOW_COPY_AND_ASSIGN(CdmResultPromise);
 };
 
-typedef CdmResultPromise<void> SimpleCdmResultPromise;
+typedef CdmResultPromise<> SimpleCdmResultPromise;
 
 }  // namespace content