Web Replay: add page-level setting to bypass the MemoryCache

Web Replay: add page-level setting to bypass the MemoryCache
https://bugs.webkit.org/show_bug.cgi?id=130728

Reviewed by Timothy Hatcher.

Source/WebCore:

When replaying a specific Page we don't want to store its cached resources in the
MemoryCache. This patch adds a page setting to prevent the page's resources from
being saved in the MemoryCache.

If Settings::usesMemoryCache() is false, page resources are given the special
SessionID bypassCacheSessionID(). The cached resource loader and memory cache
act as if the memory cache is disabled if the resource has this special session id.

Hook up ReplayController to override the memory cache setting during capture/replay.

Test: http/tests/cache/bypass-memory-cache-after-reload.html

* loader/cache/CachedResourceLoader.cpp:
(WebCore::CachedResourceLoader::requestResource):
(WebCore::CachedResourceLoader::revalidateResource):
* loader/cache/MemoryCache.cpp:
(WebCore::MemoryCache::add):
* page/Page.cpp:
(WebCore::Page::sessionID):
* page/SessionID.h:
(WebCore::SessionID::bypassCacheSessionID):
* page/Settings.cpp:
(WebCore::Settings::Settings):
* page/Settings.h:
(WebCore::Settings::setUsesMemoryCache):
(WebCore::Settings::usesMemoryCache):
* replay/ReplayController.cpp:
(WebCore::ReplayController::setForceDeterministicSettings):
* replay/ReplayController.h:
* testing/InternalSettings.cpp:
(WebCore::InternalSettings::Backup::Backup):
(WebCore::InternalSettings::Backup::restoreTo):
(WebCore::InternalSettings::setUsesMemoryCache):
* testing/InternalSettings.h:
* testing/InternalSettings.idl:

Source/WebKit2:

* UIProcess/APISession.cpp:
(API::generateID): update the base ID for generating unique sessions.

LayoutTests:

Mac WebKit2 needs different expectations because of resource load timing characteristics
introduced by the interaction of Settings::usesMemoryCache and NetworkProcess.

* http/tests/cache/bypass-memory-cache-after-reload-expected.txt: Added.
* http/tests/cache/bypass-memory-cache-after-reload.html: Added.
* platform/mac-wk2/http/tests/cache/bypass-memory-cache-after-reload-expected.txt: Added.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@166434 268f45cc-cd09-0410-ab3c-d52691b4dbfc