--- a/image/imgRequest.cpp
+++ b/image/imgRequest.cpp
@@ -380,28 +380,19 @@ nsresult imgRequest::GetFinalURI(nsIURI*
     *aURI = mFinalURI;
     NS_ADDREF(*aURI);
     return NS_OK;
   }
 
   return NS_ERROR_FAILURE;
 }
 
-bool imgRequest::IsScheme(const char* aScheme) const {
-  MOZ_ASSERT(aScheme);
-  bool isScheme = false;
-  if (NS_WARN_IF(NS_FAILED(mURI->SchemeIs(aScheme, &isScheme)))) {
-    return false;
-  }
-  return isScheme;
-}
+bool imgRequest::IsChrome() const { return mURI->SchemeIs("chrome"); }
 
-bool imgRequest::IsChrome() const { return IsScheme("chrome"); }
-
-bool imgRequest::IsData() const { return IsScheme("data"); }
+bool imgRequest::IsData() const { return mURI->SchemeIs("data"); }
 
 nsresult imgRequest::GetImageErrorCode() { return mImageErrorCode; }
 
 void imgRequest::RemoveFromCache() {
   LOG_SCOPE(gImgLog, "imgRequest::RemoveFromCache");
 
   bool isInCache = false;
 
@@ -1184,25 +1175,22 @@ imgRequest::OnRedirectVerifyCallback(nsr
   if (LOG_TEST(LogLevel::Debug)) {
     LOG_MSG_WITH_PARAM(gImgLog, "imgRequest::OnChannelRedirect", "old",
                        mFinalURI ? mFinalURI->GetSpecOrDefault().get() : "");
   }
 
   // If the previous URI is a non-HTTPS URI, record that fact for later use by
   // security code, which needs to know whether there is an insecure load at any
   // point in the redirect chain.
-  bool isHttps = false;
-  bool isChrome = false;
   bool schemeLocal = false;
-  if (NS_FAILED(mFinalURI->SchemeIs("https", &isHttps)) ||
-      NS_FAILED(mFinalURI->SchemeIs("chrome", &isChrome)) ||
-      NS_FAILED(NS_URIChainHasFlags(mFinalURI,
+  if (NS_FAILED(NS_URIChainHasFlags(mFinalURI,
                                     nsIProtocolHandler::URI_IS_LOCAL_RESOURCE,
                                     &schemeLocal)) ||
-      (!isHttps && !isChrome && !schemeLocal)) {
+      (!mFinalURI->SchemeIs("https") && !mFinalURI->SchemeIs("chrome") &&
+       !schemeLocal)) {
     MutexAutoLock lock(mMutex);
 
     // The csp directive upgrade-insecure-requests performs an internal redirect
     // to upgrade all requests from http to https before any data is fetched
     // from the network. Do not pollute mHadInsecureRedirect in case of such an
     // internal redirect.
     nsCOMPtr<nsILoadInfo> loadInfo = mChannel->LoadInfo();
     bool upgradeInsecureRequests =

--- a/image/imgRequest.h
+++ b/image/imgRequest.h
@@ -137,17 +137,16 @@ class imgRequest final : public nsIStrea
   const ImageCacheKey& CacheKey() const { return mCacheKey; }
 
   // Resize the cache entry to 0 if it exists
   void ResetCacheEntry();
 
   // OK to use on any thread.
   nsresult GetURI(nsIURI** aURI);
   nsresult GetFinalURI(nsIURI** aURI);
-  bool IsScheme(const char* aScheme) const;
   bool IsChrome() const;
   bool IsData() const;
 
   nsresult GetImageErrorCode(void);
 
   /// Returns a non-owning pointer to this imgRequest's MIME type.
   const char* GetMimeType() const { return mContentType.get(); }
 

--- a/media/webrtc/signaling/src/peerconnection/MediaTransportHandler.cpp
+++ b/media/webrtc/signaling/src/peerconnection/MediaTransportHandler.cpp
@@ -260,21 +260,20 @@ static nsresult addNrIceServer(const nsS
   // Without STUN/TURN handlers, NS_NewURI returns nsSimpleURI rather than
   // nsStandardURL. To parse STUN/TURN URI's to spec
   // http://tools.ietf.org/html/draft-nandakumar-rtcweb-stun-uri-02#section-3
   // http://tools.ietf.org/html/draft-petithuguenin-behave-turn-uri-03#section-3
   // we parse out the query-string, and use ParseAuthority() on the rest
   RefPtr<nsIURI> url;
   nsresult rv = NS_NewURI(getter_AddRefs(url), aIceUrl);
   NS_ENSURE_SUCCESS(rv, rv);
-  bool isStun = false, isStuns = false, isTurn = false, isTurns = false;
-  url->SchemeIs("stun", &isStun);
-  url->SchemeIs("stuns", &isStuns);
-  url->SchemeIs("turn", &isTurn);
-  url->SchemeIs("turns", &isTurns);
+  bool isStun = url->SchemeIs("stun");
+  bool isStuns = url->SchemeIs("stuns");
+  bool isTurn = url->SchemeIs("turn");
+  bool isTurns = url->SchemeIs("turns");
   if (!(isStun || isStuns || isTurn || isTurns)) {
     return NS_ERROR_FAILURE;
   }
   if (isStuns) {
     return NS_OK;  // TODO: Support STUNS (Bug 1056934)
   }
 
   nsAutoCString spec;

--- a/media/webrtc/signaling/src/peerconnection/PeerConnectionMedia.cpp
+++ b/media/webrtc/signaling/src/peerconnection/PeerConnectionMedia.cpp
@@ -349,19 +349,17 @@ void PeerConnectionMedia::GatherIfReady(
 
 nsresult PeerConnectionMedia::SetTargetForDefaultLocalAddressLookup() {
   Document* doc = mParent->GetWindow()->GetExtantDoc();
   if (!doc) {
     NS_WARNING("Unable to get document from window");
     return NS_ERROR_NOT_AVAILABLE;
   }
 
-  bool isFileScheme;
-  doc->GetDocumentURI()->SchemeIs("file", &isFileScheme);
-  if (!isFileScheme) {
+  if (!doc->GetDocumentURI()->SchemeIs("file")) {
     nsIChannel* channel = doc->GetChannel();
     if (!channel) {
       NS_WARNING("Unable to get channel from document");
       return NS_ERROR_NOT_AVAILABLE;
     }
 
     nsCOMPtr<nsIHttpChannelInternal> httpChannelInternal =
         do_QueryInterface(channel);

--- a/security/manager/ssl/nsSecureBrowserUIImpl.cpp
+++ b/security/manager/ssl/nsSecureBrowserUIImpl.cpp
@@ -253,25 +253,17 @@ static nsresult URICanBeConsideredSecure
   if (!innermostURI) {
     MOZ_LOG(gSecureBrowserUILog, LogLevel::Debug,
             ("  couldn't get innermost URI"));
     return NS_ERROR_FAILURE;
   }
   MOZ_LOG(gSecureBrowserUILog, LogLevel::Debug,
           ("  innermost URI is '%s'", innermostURI->GetSpecOrDefault().get()));
 
-  bool isHttps;
-  nsresult rv = innermostURI->SchemeIs("https", &isHttps);
-  if (NS_FAILED(rv)) {
-    MOZ_LOG(gSecureBrowserUILog, LogLevel::Debug,
-            ("  nsIURI->SchemeIs failed"));
-    return rv;
-  }
-
-  canBeConsideredSecure = isHttps;
+  canBeConsideredSecure = innermostURI->SchemeIs("https");
 
   return NS_OK;
 }
 
 // Helper function to get the securityInfo from a channel as a
 // nsITransportSecurityInfo. The out parameter will be set to null if there is
 // no securityInfo set.
 static void GetSecurityInfoFromChannel(