https://bugs.webkit.org/show_bug.cgi?id=96010

Reviewed by James Robinson.

Source/Platform:

Add some additional clarifying comments.

* chromium/public/WebVideoFrameProvider.h:
(Client):
(WebVideoFrameProvider):

Source/WebKit/chromium:

The key fix here is that the destructor no longer has a mutex.
The m_compositingMutex was supposedly protecting races between
~WebMediaPlayerClientImpl and setVideoFrameProviderClient. The
former is only called from the main thread and the latter is called
from the compositor thread only when the main thread is blocked (and
it already asserts that this is the case).

In addition, the m_providerMutex in CCVideoLayerImpl prevents the
destruction of WebMediaPlayerClientImpl, thus keeping the frame
acquired via getCurrentFrame alive until putCurrentFrame is called.
These functions are only called by the client, and comments are added
to the interface to better document this.

To prevent a race between load() and getCurrentFrame/putCurrentFrame
(which are called from different threads) a new m_webMediaPlayerMutex
to replace part of what the old m_compositingMutex was doing.

* src/WebMediaPlayerClientImpl.cpp:
(WebKit::WebMediaPlayerClientImpl::~WebMediaPlayerClientImpl):
(WebKit::WebMediaPlayerClientImpl::load):
(WebKit::WebMediaPlayerClientImpl::loadInternal):
(WebKit::WebMediaPlayerClientImpl::setVideoFrameProviderClient):
(WebKit::WebMediaPlayerClientImpl::getCurrentFrame):
(WebKit::WebMediaPlayerClientImpl::putCurrentFrame):
* src/WebMediaPlayerClientImpl.h:
(WebMediaPlayerClientImpl):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@128082 268f45cc-cd09-0410-ab3c-d52691b4dbfc