Bug 1518344 - P4. Don't attempt to use the RDD process if we failed to start it earlier. r=mjf,bryce,padenot

Now that launching the RDD process is fully asynchronous and no longer block the parent main thread, we can enable it on all platforms.

If we did fail to start it, we will not attempt again unless on Nightly.

Re-enable the RDD on Windows for ARM seeing that even if it did fail, it won't inconvenience the user anymore (other than the first video/audio element will take longer than usual to start)

Differential Revision: https://phabricator.services.mozilla.com/D96669

dom/media/ipc/RDDProcessManager.cpp

@@ -126,6 +126,12 @@ auto RDDProcessManager::EnsureRDDProcessAndCreateBridge(
               });
         }
 
+        if (mNumProcessAttempts &&
+            !StaticPrefs::media_rdd_retryonfailure_enabled()) {
+          // We failed to start the RDD process earlier, abort now.
+          return EnsureRDDPromise::CreateAndReject(NS_ERROR_NOT_AVAILABLE,
+                                                   __func__);
+        }
         // Launch the RDD process.
         std::vector<std::string> extraArgs;
         nsCString parentBuildID(mozilla::PlatformBuildID());
@@ -161,13 +167,16 @@ auto RDDProcessManager::EnsureRDDProcessAndCreateBridge(
 
               if (!CreateVideoBridge() ||
                   !CreateContentBridge(aOtherProcess, &endpoint)) {
+                mNumProcessAttempts++;
                 return EnsureRDDPromise::CreateAndReject(NS_ERROR_NOT_AVAILABLE,
                                                          __func__);
               }
+              mNumProcessAttempts = 0;
               return EnsureRDDPromise::CreateAndResolve(std::move(endpoint),
                                                         __func__);
             },
             [this](nsresult aError) {
+              mNumProcessAttempts++;
               DestroyProcess();
               return EnsureRDDPromise::CreateAndReject(aError, __func__);
             });

modules/libpref/init/StaticPrefList.yaml

@@ -7171,11 +7171,7 @@
 - name: media.rdd-process.enabled
   type: RelaxedAtomicBool
 #if defined(XP_WIN)
-#if defined(_ARM64_)
-  value: false
-#else
   value: true
-#endif
 #elif defined(XP_MACOSX)
   value: true
 #elif defined(XP_LINUX) && !defined(ANDROID)
@@ -7185,6 +7181,11 @@
 #endif
   mirror: always
 
+- name: media.rdd-retryonfailure.enabled
+  type: RelaxedAtomicBool
+  value: @IS_NIGHTLY_BUILD@
+  mirror: always
+
 - name: media.rdd-process.startup_timeout_ms
   type: RelaxedAtomicInt32
   value: 5000