Load CMA backend from shared library

* CMA backend interfaces moved into chromecast/public/media
* CMA backend implementation loaded from libcast_media through
  CastMediaShlib
* Backend API changes to remove dependency on Chromium types:
  * DecryptContext replaced with CastKeySystem
  * scoped_refptr replaced with raw pointers
  * In particular, DecoderBufferBase replaced in the backend API
    with non-refcounted DecoderBuffer.  In order to allow us to keep
    using refcounting and in particular use DecoderBufferBase in the
    rest of our pipeline, it gets wrapped in a DecoderBufferImpl
    (implementation of DecoderBuffer) for passing to the backend. So
    backends must delete the buffer pointer they're given but this is
    actually just decrementing the refcount on the underlying buffer.
  * base::Callback replaced with abstract interfaces
  * base::TimeDelta replaced with chromecast::TimeDelta in backend
    interface, essentially a stripped-down copy
  * NonThreadSafe removed (implementations can use ThreadChecker)
* TaskRunner interface provides PostTask/PostDelayedTask service to
  backend implementations
* Backend ownership / factory model changed.  Now, backend
  implementations return a MediaPipelineBackend which manages ownership
  and hookup of all the components.  It returns access to them as raw
  pointers.  The pipeline manages the lifetime of the MediaPipelineBackend
  instance.
* GetIsCodecSupportedOnChromecast refactored to remove calls back into
  cast_shell from backends (implementation can just return 'default' to
  indicate default logic should apply, including HDMI capabilities.

BUG=508534

Review URL: https://codereview.chromium.org/1257013003

Cr-Commit-Position: refs/heads/master@{#342370}

1 files changed, 2 insertions, 2 deletions

diff --git a/chromecast/media/cdm/browser_cdm_cast.h b/chromecast/media/cdm/browser_cdm_cast.h
index 0e24a51..a4c80fb 100644
--- a/chromecast/media/cdm/browser_cdm_cast.h
+++ b/chromecast/media/cdm/browser_cdm_cast.h
@@ -28,7 +28,7 @@ class PlayerTrackerImpl;
 
 namespace chromecast {
 namespace media {
-class DecryptContext;
+class DecryptContextImpl;
 
 // BrowserCdmCast is an extension of BrowserCdm that provides common
 // functionality across CDM implementations.
@@ -60,7 +60,7 @@ class BrowserCdmCast : public ::media::BrowserCdm {
   // Returns the decryption context needed to decrypt frames encrypted with
   // |key_id|.
   // Returns null if |key_id| is not available.
-  virtual scoped_refptr<DecryptContext> GetDecryptContext(
+  virtual scoped_ptr<DecryptContextImpl> GetDecryptContext(
       const std::string& key_id) const = 0;
 
  protected: