Update supported key system info from browser process if needed.

content/renderer/media/crypto/key_systems.cc

Index: content/renderer/media/crypto/key_systems.cc
diff --git a/content/renderer/media/crypto/key_systems.cc b/content/renderer/media/crypto/key_systems.cc
index 6cd82189a2e94761b6048d6792a06841798706c5..2152378a885bc42d89d83783731f496f543224b1 100644
--- a/content/renderer/media/crypto/key_systems.cc
+++ b/content/renderer/media/crypto/key_systems.cc
@@ -10,6 +10,7 @@
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/strings/string_util.h"
+#include "base/time/time.h"
 #include "content/public/common/content_client.h"
 #include "content/public/common/eme_codec.h"
 #include "content/public/renderer/content_renderer_client.h"
@@ -87,6 +88,8 @@ class KeySystems {
  public:
   static KeySystems& GetInstance();
 
+  void UpdateIfNeeded();
+
   bool IsConcreteSupportedKeySystem(const std::string& key_system);
 
   bool IsSupportedKeySystemWithMediaMimeType(
@@ -104,6 +107,8 @@ class KeySystems {
   void AddCodecMask(const std::string& codec, uint32 mask);
 
  private:
+  void UpdateSupportedKeySystems();
+
   void AddConcreteSupportedKeySystems(
       const std::vector<KeySystemInfo>& concrete_key_systems);
 
@@ -161,12 +166,15 @@ class KeySystems {
   CodecMaskMap container_codec_masks_;
   CodecMaskMap codec_masks_;
 
+  base::Time last_update_time_;
+
   DISALLOW_COPY_AND_ASSIGN(KeySystems);
 };
 
 static base::LazyInstance<KeySystems> g_key_systems = LAZY_INSTANCE_INITIALIZER;
 
 KeySystems& KeySystems::GetInstance() {
+  g_key_systems.Get().UpdateIfNeeded();
   return g_key_systems.Get();
 }
 
@@ -187,14 +195,45 @@ KeySystems::KeySystems() {
     codec_masks_[codec_mask.type] = codec_mask.mask;
   }
 
+  UpdateSupportedKeySystems();
+
+#if defined(WIDEVINE_CDM_AVAILABLE)
+  key_systems_support_uma_.AddKeySystemToReport(kWidevineKeySystem);
+#endif  // defined(WIDEVINE_CDM_AVAILABLE)
+}
+
+void KeySystems::UpdateIfNeeded() {
+#if defined(WIDEVINE_CDM_AVAILABLE) && defined(WIDEVINE_CDM_IS_COMPONENT)
+  if (IsConcreteSupportedKeySystem(kWidevineKeySystem))
+    return;
+
+  // The update could involve a sync IPC to the browser process. Use a minimum
+  // update interval to avoid unnecessary frequent IPC to the browser.
+  static const int kMinUpdateIntervalInSeconds = 5;
+  base::Time now = base::Time::Now();
+  if (now - last_update_time_ <
+      base::TimeDelta::FromSeconds(kMinUpdateIntervalInSeconds)) {
+    return;
+  }
+
+  UpdateSupportedKeySystems();
+#endif
+}
+
+void KeySystems::UpdateSupportedKeySystems() {
+  DVLOG(2) << __FUNCTION__;

[xhwang, 2014/07/18 00:44:15]

I'll remove this.

+  concrete_key_system_map_.clear();
+  parent_key_system_map_.clear();
+
+  // Build KeySystemInfo.
   std::vector<KeySystemInfo> key_systems_info;
   GetContentClient()->renderer()->AddKeySystems(&key_systems_info);
   // Clear Key is always supported.
   AddClearKey(&key_systems_info);
+
   AddConcreteSupportedKeySystems(key_systems_info);
-#if defined(WIDEVINE_CDM_AVAILABLE)
-  key_systems_support_uma_.AddKeySystemToReport(kWidevineKeySystem);
-#endif  // defined(WIDEVINE_CDM_AVAILABLE)
+
+  last_update_time_ = base::Time::Now();
 }
 
 void KeySystems::AddConcreteSupportedKeySystems(