Handle plugin instance crash in ContentDecryptorDelegate.

content/renderer/pepper/content_decryptor_delegate.h

Index: content/renderer/pepper/content_decryptor_delegate.h
diff --git a/content/renderer/pepper/content_decryptor_delegate.h b/content/renderer/pepper/content_decryptor_delegate.h
index 4e5a4bd5661c4644305e2e7d96313dfec42de425..d3fdc532ef398c7bf3b0986e4b736cb11dfa38db 100644
--- a/content/renderer/pepper/content_decryptor_delegate.h
+++ b/content/renderer/pepper/content_decryptor_delegate.h
@@ -49,6 +49,8 @@ class ContentDecryptorDelegate {
       const media::SessionClosedCB& session_closed_cb,
       const media::SessionErrorCB& session_error_cb);
 
+  void InstanceCrashed();
+
   // Provides access to PPP_ContentDecryptor_Private.
   bool CreateSession(uint32 session_id,
                      const std::string& type,
@@ -109,8 +111,11 @@ class ContentDecryptorDelegate {
   class TrackableCallback {
    public:
     TrackableCallback() : id_(0u) {}
-    // TODO(xhwang): Check that no callback is pending in dtor.
-    ~TrackableCallback() {};
+    ~TrackableCallback() {
+      // Callbacks must be satisfied.
+      DCHECK_EQ(id_, 0u);
+      DCHECK(is_null());
+    };
 
     bool Matches(uint32_t id) const { return id == id_; }
 
@@ -162,6 +167,8 @@ class ContentDecryptorDelegate {
                               media::SampleFormat sample_format,
                               media::Decryptor::AudioBuffers* frames);
 
+  void CancelAllPendingCallbacks();
+
   const PP_Instance pp_instance_;
   const PPP_ContentDecryptor_Private* const plugin_decryption_interface_;
 
@@ -203,6 +210,9 @@ class ContentDecryptorDelegate {
   base::WeakPtr<ContentDecryptorDelegate> weak_this_;
   base::WeakPtrFactory<ContentDecryptorDelegate> weak_ptr_factory_;
 
+  // State of the current instance. Set to false if the plugin instance crashed.
+  bool is_valid_;
+
   DISALLOW_COPY_AND_ASSIGN(ContentDecryptorDelegate);
 };