Replace use of frame->Loader().Client() with frame->Client().

Make FrameLoader::Client() private so that it cannot be used to retrieve the
LocalFrameClient in new cases anymore.

Bug: 736673
Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: Ia890099ca6dc03babb296413c15adda66b460b00
Reviewed-on: https://chromium-review.googlesource.com/557559
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Stuart Langley <slangley@chromium.org>
Cr-Commit-Position: refs/heads/master@{#483669}

• third_party/WebKit/Source/core/html/HTMLLinkElement.cpp[diff]
• third_party/WebKit/Source/core/html/HTMLMetaElement.cpp[diff]
• third_party/WebKit/Source/core/html/HTMLObjectElement.cpp[diff]
• third_party/WebKit/Source/core/html/HTMLPlugInElement.cpp[diff]
• third_party/WebKit/Source/core/html/LinkManifest.cpp[diff]
• third_party/WebKit/Source/core/html/LinkStyle.cpp[diff]
• third_party/WebKit/Source/core/html/parser/XSSAuditorDelegate.cpp[diff]
• third_party/WebKit/Source/core/loader/CookieJar.cpp[diff]
• third_party/WebKit/Source/core/loader/FrameLoader.h[diff]
• third_party/WebKit/Source/core/loader/MixedContentChecker.cpp[diff]
• third_party/WebKit/Source/core/loader/NavigationScheduler.cpp[diff]
• third_party/WebKit/Source/core/loader/PingLoader.cpp[diff]
• third_party/WebKit/Source/core/loader/appcache/ApplicationCacheHost.cpp[diff]
• third_party/WebKit/Source/core/workers/SharedWorker.cpp[diff]
• third_party/WebKit/Source/core/xml/XSLTProcessor.cpp[diff]
• third_party/WebKit/Source/modules/donottrack/NavigatorDoNotTrack.cpp[diff]
• third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.cpp[diff]
• third_party/WebKit/Source/modules/serviceworkers/ServiceWorkerContainerClient.cpp[diff]
• third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp[diff]
• third_party/WebKit/Source/web/tests/LocalFrameClientImplTest.cpp[diff]