Introduce SharedDictionaryAccessObserver Mojo IPC

This CL introduces SharedDictionaryAccessObserver Mojo IPC which is used
to notify the usage of shared dictionary from the network service to the
browser process. When a shared dictionary is used
WebContentsObserver::OnSharedDictionaryAccessed() will be asynchronously
invoked.

We will use this to show the origin in the "Cookies and site data"
dialog (crbug.com/1413922#c59) when a shared dictionary is used in
succeeding CLs

For navigation request:
  - content::NavigationRequest in the browser process implements the
    observer interface.
  - NavigationRequest::OnStartChecksComplete() passes the mojo remote
    interface of the observer through NavigationURLLoader::Create(),
    NavigationURLLoaderImpl() and CreateResourceRequest() into
    network::ResourceRequest's TrustedParams' shared_dictionary_observer
    field.
  - In the network process, URLLoaderFactory gets the mojo remote
    interface of the observer from `resource_request`, and passes it to
    SharedDictionaryAccessChecker.
  - The SharedDictionaryAccessChecker is passed to URLLoader. URLLoader
    calls IsAllowedToRead() when dictionary is used. And the checker
    sends the OnSharedDictionaryAccessed() IPC.
  - When content::NavigationRequest receives the IPC, it calls:
      NavigatorDelegate::OnSharedDictionaryAccessed()
       -> WebContentsImpl::OnSharedDictionaryAccessed()
        -> WebContentsObserver::OnSharedDictionaryAccessed()

For subresource request:
  - content::RenderFrameHostImpl in the browser process implements the
    observer interface.
  - URLLoaderFactoryParamsHelper::CreateForFrame() is called when
    committing a page navigation. The method sets the mojo remote
    interface of the observer to URLLoaderFactoryParams's
    shared_dictionary_observer field.
  - In the network process, CorsURLLoaderFactory receives and keeps the
    remote interface.
  - For dictionary read case: URLLoaderFactory passes the pointer of the
    remote interface to SharedDictionaryAccessChecker. And The
    SharedDictionaryAccessChecker is passed to URLLoader. URLLoader
    calls IsAllowedToRead() when dictionary is used. And the checker
    sends the OnSharedDictionaryAccessed() IPC.
  - For dictionary write case: When CorsURLLoader receives a response,
    it passes the pointer of the remote interface to
    SharedDictionaryAccessChecker. And the checker's IsAllowedToWrite()
    is called by SharedDictionaryStorage when there is a valid
    use-as-dictionary header.
  - When content::RenderFrameHostImpl receives the IPC, it calls:
      RenderFrameHostDelegate::OnSharedDictionaryAccessed()
       -> WebContentsImpl::OnSharedDictionaryAccessed()
        -> WebContentsObserver::OnSharedDictionaryAccessed()

For shared worker and service worker case:
  - StoragePartitionImpl::ServiceWorkerSharedDictionaryAccessObserver
    in the browser process implements the observer interface.
  - URLLoaderFactoryParamsHelper::CreateForWorker() sets the mojo remote
    interface of the observer to URLLoaderFactoryParams's
    shared_dictionary_observer field.
  - When ServiceWorkerSharedDictionaryAccessObserver receives the IPC,
    it calls:
      RenderFrameHostImpl::OnSharedDictionaryAccessed()
        RenderFrameHostDelegate::OnSharedDictionaryAccessed()
        -> WebContentsImpl::OnSharedDictionaryAccessed()
          -> WebContentsObserver::OnSharedDictionaryAccessed()

Bug: 1413922
Change-Id: I71827fe43912de2d7c2271123717260772122cbf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4617698
Reviewed-by: Takashi Toyoshima <toyoshim@chromium.org>
Reviewed-by: Adam Rice <ricea@chromium.org>
Commit-Queue: Tsuyoshi Horo <horo@chromium.org>
Reviewed-by: Rakina Zata Amni <rakina@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1163489}