DevTools: introduce DevToolsAgentHost
We need an abstract interface that would encapsulate communication
with inspected instance DeviTools agent. It'is going to have different
implementations at least for render views and shared workers. This
patch leaves all methods on the DevToolsManager that accept inspected
RenderViewHost just for convenience. Eventually DevToolsManager should
operate in terms of DevToolsAgentHost and DevToolsClientHost only.
BUG=None
TEST=DevTools tests
Review URL: http://codereview.chromium.org/
7648032
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@96906 0039d316-1c4b-4281-b951-d872f2087c98