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 352817dd01170776d79e1f2dfad98b16667b3b09..b5a6cc468efe01367a0f4eb8ecfea8492e16ee3e 100644
--- a/content/renderer/pepper/content_decryptor_delegate.h
+++ b/content/renderer/pepper/content_decryptor_delegate.h
@@ -48,6 +48,8 @@ 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,
@@ -185,6 +187,8 @@ class ContentDecryptorDelegate {
   base::WeakPtr<ContentDecryptorDelegate> weak_this_;
   base::WeakPtrFactory<ContentDecryptorDelegate> weak_ptr_factory_;
 
+  bool is_instance_crashed_;

[xhwang, 2013/12/28 01:00:28]

I am debating on this. Probably when the plugin is crashed, we should just
destroy this ContentDecryptorDelegate object. WDYT?

[ddorwin, 2014/01/07 19:28:48]

You can't simply destroy this object without informing PpapiDecryptor and higher
layers to stop calling Decrypt(), etc. PpapiDecryptor assumes there is always a
delegate, so you'd have to add such checks there anyway. Higher-level code might
already have checks for decryptor_ != NULL, but it's also more likely that there
are assumptions about the decryptor/decoder not changing.

To fully clean up, we would tell PpapiDecryptor, which would clean up the WHP as
well. (Such a change would also need the delegate != NULL checks mentioned
above.) However, that's a lot of complexity for an unexpected case.

is_instance_crashed_ isn't great, but it's simpler and isolated. Maybe it should
be is_valid_ or something similar that is more generic instead.

Pushing this knowledge into PpapiDecryptor would allow us to eliminate the
(previously always true) bool return values from most of the methods, which is
nice since it removes ambiguity. I don't think I'd go further up the stack than
that, though.

[xhwang, 2014/01/07 20:48:34]

Thanks for the comments. In summary, notifying PpapiDecryptor would allow us to
do more cleanups, but that requires more complexity. Since this is only a corner
case, I am inclined to keep |is_valid_| to make this CL simple. WDYT?

BTW, could you take a look at https://codereview.chromium.org/105743010/ first,
which would make this CL simpler? Thanks!

[ddorwin, 2014/01/07 23:59:01]

Agreed and done.

+
   DISALLOW_COPY_AND_ASSIGN(ContentDecryptorDelegate);
 };