Allow suppressed EME canPlayType() responses to be overridden with a flag.

Adds --override-encrypted-media-canplaytype and the corresponding flag.

BUG=252967
TBR=jochen@chromium.org

Review URL: https://chromiumcodereview.appspot.com/17459003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@208096 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/about_flags.cc

@@ -754,6 +754,13 @@ const Experiment kExperiments[] = {
     kOsDesktop,
     SINGLE_VALUE_TYPE(switches::kDisableLegacyEncryptedMedia)
   },
+  {
+    "override-encrypted-media-canplaytype",
+    IDS_FLAGS_ENCRYPTED_MEDIA_CANPLAYTYPE_OVERRIDE_NAME,
+    IDS_FLAGS_ENCRYPTED_MEDIA_CANPLAYTYPE_OVERRIDE_DESCRIPTION,
+    kOsMac | kOsWin,
+    SINGLE_VALUE_TYPE(switches::kOverrideEncryptedMediaCanPlayType)
+  },
   {
     "enable-opus-playback",
     IDS_FLAGS_ENABLE_OPUS_PLAYBACK_NAME,

content/browser/renderer_host/render_process_host_impl.cc

@@ -894,6 +894,7 @@ void RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer(
     switches::kEnableDelegatedRenderer,
     switches::kEnableEncryptedMedia,
     switches::kDisableLegacyEncryptedMedia,
+    switches::kOverrideEncryptedMediaCanPlayType,
     switches::kEnableExperimentalWebKitFeatures,
     switches::kEnableFixedLayout,
     switches::kEnableDeferredImageDecoding,

media/base/media_switches.cc

@@ -21,6 +21,10 @@ const char kEnableVp8AlphaPlayback[] = "enable-vp8-alpha-playback";
 // Set number of threads to use for video decoding.
 const char kVideoThreads[] = "video-threads";
 
+// Override suppressed responses to canPlayType().
+const char kOverrideEncryptedMediaCanPlayType[] =
+    "override-encrypted-media-canplaytype";
+
 #if defined(GOOGLE_TV)
 // Use external video surface for video with more than or equal pixels to
 // specified value. For example, value of 0 will enable external video surface

media/base/media_switches.h

@@ -22,6 +22,8 @@ MEDIA_EXPORT extern const char kEnableVp8AlphaPlayback[];
 
 MEDIA_EXPORT extern const char kVideoThreads[];
 
+MEDIA_EXPORT extern const char kOverrideEncryptedMediaCanPlayType[];
+
 #if defined(GOOGLE_TV)
 MEDIA_EXPORT extern const char kUseExternalVideoSurfaceThresholdInPixels[];
 #endif

webkit/renderer/media/crypto/key_systems.cc

@@ -112,6 +112,11 @@ bool KeySystems::IsSupportedKeySystemWithMediaMimeType(
     const std::string& mime_type,
     const std::vector<std::string>& codecs,
     const std::string& key_system) {
+  // This method is only used by the canPlaytType() path (not the EME methods),
+  // so we check for suppressed key_systems here.
+  if(IsCanPlayTypeSuppressed(key_system))
+    return false;
+
   if (codecs.empty())
     return IsSupportedKeySystemWithContainerAndCodec(
         mime_type, std::string(), key_system);

webkit/renderer/media/crypto/key_systems_info.cc

@@ -6,6 +6,8 @@
 
 #include "widevine_cdm_version.h" // In SHARED_INTERMEDIATE_DIR.
 
+// The following must be after widevine_cdm_version.h.
+
 #if defined(WIDEVINE_CDM_AVAILABLE) && \
     defined(OS_LINUX) && !defined(OS_CHROMEOS)
 #include <gnu/libc-version.h>
@@ -13,6 +15,11 @@
 #include "base/version.h"
 #endif
 
+#if defined(DISABLE_WIDEVINE_CDM_CANPLAYTYPE)
+#include "base/command_line.h"
+#include "media/base/media_switches.h"
+#endif
+
 namespace webkit_media {
 
 static const char kClearKeyKeySystem[] = "webkit-org.w3.clearkey";
@@ -23,7 +30,6 @@ static const char kExternalClearKeyKeySystem[] =
 #if defined(WIDEVINE_CDM_AVAILABLE)
 // TODO(ddorwin): Automatically support parent systems: http://crbug.com/164303.
 static const char kWidevineBaseKeySystem[] = "com.widevine";
-#endif  // defined(WIDEVINE_CDM_AVAILABLE)
 
 #if defined(WIDEVINE_CDM_CENC_SUPPORT_AVAILABLE)
 // The supported codecs depend on what the CDM provides.
@@ -45,6 +51,12 @@ static const char kWidevineAudioMp4Codecs[] =
 #endif
 #endif  // defined(WIDEVINE_CDM_CENC_SUPPORT_AVAILABLE)
 
+static inline bool IsWidevine(const std::string& key_system) {
+  return key_system == kWidevineKeySystem ||
+         key_system == kWidevineBaseKeySystem;
+}
+#endif  // defined(WIDEVINE_CDM_AVAILABLE)
+
 const MediaFormatAndKeySystem kSupportedFormatKeySystemCombinations[] = {
   // Clear Key.
   { "video/webm", "vorbis,vp8,vp8.0", kClearKeyKeySystem },
@@ -64,10 +76,6 @@ const MediaFormatAndKeySystem kSupportedFormatKeySystemCombinations[] = {
 
 #if defined(WIDEVINE_CDM_AVAILABLE)
   // Widevine.
-  // See http://crbug.com/237627.
-#if defined(DISABLE_WIDEVINE_CDM_CANPLAYTYPE)
-  { "", "", kWidevineKeySystem },
-#else
   { "video/webm", "vorbis,vp8,vp8.0", kWidevineKeySystem },
   { "audio/webm", "vorbis", kWidevineKeySystem },
   { "video/webm", "vorbis,vp8,vp8.0", kWidevineBaseKeySystem },
@@ -80,7 +88,6 @@ const MediaFormatAndKeySystem kSupportedFormatKeySystemCombinations[] = {
   { "audio/mp4", kWidevineAudioMp4Codecs, kWidevineBaseKeySystem },
 #endif  // defined(WIDEVINE_CDM_CENC_SUPPORT_AVAILABLE)
 #endif  // defined(GOOGLE_CHROME_BUILD) || defined(USE_PROPRIETARY_CODECS)
-#endif  // defined(DISABLE_WIDEVINE_CDM_CANPLAYTYPE)
 #endif  // WIDEVINE_CDM_AVAILABLE
 };
 
@@ -117,8 +124,7 @@ const int kNumKeySystemToUUIDMapping =
 bool IsSystemCompatible(const std::string& key_system) {
 #if defined(WIDEVINE_CDM_AVAILABLE) && \
     defined(OS_LINUX) && !defined(OS_CHROMEOS)
-  if (key_system == kWidevineKeySystem ||
-      key_system == kWidevineBaseKeySystem) {
+  if (IsWidevine(key_system)) {
     Version glibc_version(gnu_get_libc_version());
     DCHECK(glibc_version.IsValid());
     return !glibc_version.IsOlderThan(WIDEVINE_CDM_MIN_GLIBC_VERSION);
@@ -127,6 +133,17 @@ bool IsSystemCompatible(const std::string& key_system) {
   return true;
 }
 
+bool IsCanPlayTypeSuppressed(const std::string& key_system) {
+#if defined(DISABLE_WIDEVINE_CDM_CANPLAYTYPE)
+  // See http://crbug.com/237627.
+  if (IsWidevine(key_system) &&
+      !CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEncryptedMediaCanPlayTypeOverride))
+    return true;
+#endif
+  return false;
+}
+
 std::string KeySystemNameForUMAGeneric(const std::string& key_system) {
   if (key_system == kClearKeyKeySystem)
     return "ClearKey";

webkit/renderer/media/crypto/key_systems_info.h

@@ -55,6 +55,9 @@ extern const int kNumKeySystemToUUIDMapping;
 // Returns whether |key_system| is compatible with the user's system.
 bool IsSystemCompatible(const std::string& key_system);
 
+// Returns true if canPlayType should return an empty string for |key_system|.
+bool IsCanPlayTypeSuppressed(const std::string& key_system);
+
 // Returns the name that UMA will use for the given |key_system|.
 // This function can be called frequently. Hence this function should be
 // implemented not to impact performance.

webkit/renderer/media/crypto/key_systems_unittest.cc

@@ -540,7 +540,13 @@ TEST_F(KeySystemsTest,
 //
 
 TEST_F(KeySystemsTest, Widevine_Basic) {
+#if defined(WIDEVINE_CDM_AVAILABLE) && \
+    defined(DISABLE_WIDEVINE_CDM_CANPLAYTYPE)
+  EXPECT_TRUE(IsSupportedKeySystem(WebString::fromUTF8(kWidevineAlpha)));
+#else
   EXPECT_WV(IsSupportedKeySystem(WebString::fromUTF8(kWidevineAlpha)));
+#endif
+
   EXPECT_WV(IsSupportedKeySystemWithMediaMimeType(
       "video/webm", no_codecs(), kWidevineAlpha));
 
@@ -571,7 +577,12 @@ TEST_F(KeySystemsTest, Widevine_Basic) {
 TEST_F(KeySystemsTest, Widevine_Parent) {
   const char* const kWidevineParent = kWidevine;
 
+#if defined(WIDEVINE_CDM_AVAILABLE) && \
+    defined(DISABLE_WIDEVINE_CDM_CANPLAYTYPE)
+  EXPECT_TRUE(IsSupportedKeySystem(WebString::fromUTF8(kWidevineParent)));
+#else
   EXPECT_WV(IsSupportedKeySystem(WebString::fromUTF8(kWidevineParent)));
+#endif
   EXPECT_WV(IsSupportedKeySystemWithMediaMimeType(
       "video/webm", no_codecs(), kWidevineParent));