EME: Correctly handle container-only contentType strings

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

Index: third_party/WebKit/Source/modules/encryptedmedia/NavigatorRequestMediaKeySystemAccess.cpp
diff --git a/third_party/WebKit/Source/modules/encryptedmedia/NavigatorRequestMediaKeySystemAccess.cpp b/third_party/WebKit/Source/modules/encryptedmedia/NavigatorRequestMediaKeySystemAccess.cpp
index fbeffbbd610019dfd1d6c4bb317d754e1ea229bb..934523e36fb9e728b800db080c92434ee060f0ce 100644
--- a/third_party/WebKit/Source/modules/encryptedmedia/NavigatorRequestMediaKeySystemAccess.cpp
+++ b/third_party/WebKit/Source/modules/encryptedmedia/NavigatorRequestMediaKeySystemAccess.cpp
@@ -27,6 +27,7 @@
 #include "public/platform/WebVector.h"
 #include "wtf/Vector.h"
 #include "wtf/text/WTFString.h"
+#include <algorithm>
 
 namespace blink {
 
@@ -79,6 +80,11 @@ static WebVector<WebEncryptedMediaSessionType> convertSessionTypes(const Vector<
     return result;
 }
 
+static bool AreCodecsSpecified(const WebMediaKeySystemMediaCapability& capability)
+{
+    return !capability.codecs.isEmpty();
+}
+
 // This class allows capabilities to be checked and a MediaKeySystemAccess
 // object to be created asynchronously.
 class MediaKeySystemAccessInitializer final : public EncryptedMediaRequest {
@@ -111,6 +117,12 @@ private:
     // See http://crbug.com/482277
     void checkVideoCapabilityRobustness() const;
 
+    // Generate warning and report UMA if configuration contains a
+    // container-only contentType string.
+    // TODO(jrummell): Remove once this is no longer allowed.
+    // See http://crbug.com/605661.
+    void checkEmptyCodecs(const WebMediaKeySystemConfiguration&);
+
     Member<ScriptPromiseResolver> m_resolver;
     const String m_keySystem;
     WebVector<WebMediaKeySystemConfiguration> m_supportedConfigurations;
@@ -154,6 +166,8 @@ MediaKeySystemAccessInitializer::MediaKeySystemAccessInitializer(ScriptState* sc
 
 void MediaKeySystemAccessInitializer::requestSucceeded(WebContentDecryptionModuleAccess* access)
 {
+    checkEmptyCodecs(access->getConfiguration());
+
     m_resolver->resolve(new MediaKeySystemAccess(m_keySystem, adoptPtr(access)));
     m_resolver.clear();
 }
@@ -202,6 +216,42 @@ void MediaKeySystemAccessInitializer::checkVideoCapabilityRobustness() const
     }
 }
 
+void MediaKeySystemAccessInitializer::checkEmptyCodecs(const WebMediaKeySystemConfiguration& config)
+{
+    // This is only checking for empty codecs in the selected configuration,
+    // as apps may pass container only contentType strings for compatibility
+    // with other implementations.
+    // This will only check that all returned capabilities do not contain
+    // codecs. This allows apps to provide both (one with codecs, one without)

[ddorwin, 2016/04/27 23:33:48]

Since we don't think this is useful, perhaps we should just say, "This avoids
alerting on configurations that will continue to succeed..."

[jrummell, 2016/04/28 01:32:47]

Done.

+    // for compatibility reasons, and that will continue to succeed in the
+    // future once strict checking is enforced.
+    bool areAllAudioCodecsEmpty = false;
+    if (config.hasAudioCapabilities && !config.audioCapabilities.isEmpty()) {
+        areAllAudioCodecsEmpty = std::find_if(config.audioCapabilities.begin(), config.audioCapabilities.end(), AreCodecsSpecified)
+            == config.audioCapabilities.end();

[jrummell, 2016/04/26 21:23:57]

Tried to split this into meaningful lines so that it's not one long line, but
this is all I can get "git clang-format --style Webkit", "git cl format", and
presubmit to agree on.

+
+        DEFINE_THREAD_SAFE_STATIC_LOCAL(EnumerationHistogram, emptyAudioCodecsHistogram,
+            new EnumerationHistogram("Media.EME.RequestMediaKeySystemAccess.SelectedAudioContentTypeWithoutCodecs", 2));

[ddorwin, 2016/04/27 23:33:48]

Hmm. This isn't strictly accurate since we are checking for _all_.

AllSelectedAudioContentTypeMisingCodecs?

[jrummell, 2016/04/28 01:32:47]

Switched to UseCounter.

+        emptyAudioCodecsHistogram.count(areAllAudioCodecsEmpty);
+    }
+
+    bool areAllVideoCodecsEmpty = false;
+    if (config.hasVideoCapabilities && !config.videoCapabilities.isEmpty()) {
+        areAllVideoCodecsEmpty = std::find_if(config.videoCapabilities.begin(), config.videoCapabilities.end(), AreCodecsSpecified)
+            == config.videoCapabilities.end();
+
+        DEFINE_THREAD_SAFE_STATIC_LOCAL(EnumerationHistogram, emptyVideoCodecsHistogram,
+            new EnumerationHistogram("Media.EME.RequestMediaKeySystemAccess.SelectedVideoContentTypeWithoutCodecs", 2));
+        emptyVideoCodecsHistogram.count(areAllVideoCodecsEmpty);
+    }
+
+    if (areAllAudioCodecsEmpty || areAllVideoCodecsEmpty) {
+        m_resolver->getExecutionContext()->addConsoleMessage(ConsoleMessage::create(JSMessageSource, WarningMessageLevel,

[ddorwin, 2016/04/27 23:33:48]

Should we use countDeprecation() instead of a separate histogram? UseCounter
isn't as easy to use as our own histogram, but it does deal with logging
consistently.

[jrummell, 2016/04/28 01:32:47]

Done (along with counting the successes).

+            "contentType strings without codecs will not be supported in the future."
+            "Please specify the desired codec(s) as part of the contentType."));
+    }
+}
+
 } // namespace
 
 ScriptPromise NavigatorRequestMediaKeySystemAccess::requestMediaKeySystemAccess(