If a previously loaded resource is later stored to the disk cache, replace the buffer with MMAP'ed memory.
<rdar://problem/13414154> and https://bugs.webkit.org/show_bug.cgi?id=112943

Reviewed by Geoff Garen.

Source/WebCore:

No new tests (No change in behavior.)

Give SharedBuffer the ability to replace its contents from another SharedBuffer:
* platform/SharedBuffer.h:
* platform/cf/SharedBufferCF.cpp:
(WebCore::SharedBuffer:: tryReplaceContentsWithPlatformBuffer):

Forward along SharedBuffer's new ability to ResourceBuffer:
* loader/mac/ResourceBuffer.mm:
(WebCore::ResourceBuffer:: tryReplaceSharedBufferContents):
* loader/ResourceBuffer.h:

Give CachedResource the ability to replace its encoded data buffer if appropriate:
* loader/cache/CachedResource.cpp:
(WebCore::CachedResource:: tryReplaceEncodedData):
* loader/cache/CachedResource.h:

* WebCore.exp.in:

Source/WebKit2:

Add a timer that will try to look up the disk cached buffer for the resource a few seconds after the load
completes and - if the resource is disk backed - send it to the WebProcess for sharing:
* NetworkProcess/NetworkResourceLoader.cpp:
(WebKit::NetworkResourceLoader::NetworkResourceLoader):
(WebKit::NetworkResourceLoader::diskCacheTimerFired):
(WebKit::NetworkResourceLoader::didReceiveResponse):
(WebKit::NetworkResourceLoader::didReceiveData):
(WebKit::NetworkResourceLoader::didFinishLoading):
* NetworkProcess/NetworkResourceLoader.h:

* NetworkProcess/mac/NetworkResourceLoaderMac.mm:
(WebKit::NetworkResourceLoader::tryGetShareableHandleForResource):

Refactor SharedMemory to remove the unnecessary vm_copy and only vm_allocate when an appropriate buffer
doesn't already exist:
* Platform/SharedMemory.h:
* Platform/mac/SharedMemoryMac.cpp:
(WebKit::SharedMemory::create):
(WebKit::SharedMemory::createFromVMBuffer):
(WebKit::SharedMemory::~SharedMemory):

Give ShareableResource the ability to create a CFDataRef that wraps "this", and return it in a SharedBuffer:
* Shared/ShareableResource.cpp:
(WebKit::shareableResourceDeallocate):
(WebKit::createShareableResourceDeallocator):
(WebKit::ShareableResource::Handle::tryWrapInSharedBuffer):
* Shared/ShareableResource.h:

* Shared/WebCoreArgumentCoders.cpp: Encode/decode the cache partition for ResourceRequest.

* WebProcess/Network/NetworkProcessConnection.cpp:
(WebKit::NetworkProcessConnection::didReceiveMessage):
(WebKit::NetworkProcessConnection::didCacheResource): Lookup the CachedResource in the WebCore memory cache
  and try to replace its encoded data with the shared mmap'ed buffer.
* WebProcess/Network/NetworkProcessConnection.h:
* WebProcess/Network/NetworkProcessConnection.messages.in:

* WebProcess/Network/WebResourceLoader.cpp:
(WebKit::WebResourceLoader::didReceiveResource):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146544 268f45cc-cd09-0410-ab3c-d52691b4dbfc