Revert of Add --root-layer-scrolls. (patchset #2 id:20001 of...

Revert of Add --root-layer-scrolls. (patchset #2 id:20001 of https://codereview.chromium.org/662973003/)

Reason for revert:
This CL causes build failure:
http://build.chromium.org/p/chromium.chromiumos/buildstatus?builder=Linux%20ChromiumOS%20Builder%20%28dbg%29&number=54070

The error log is:
FAILED: /b/build/goma/gomacc ../../third_party/llvm-build/Release+Asserts/bin/clang++ (snip) -o interactive_ui_tests (snip)
obj/chrome/libbrowser_chromeos.a(obj/chrome/browser/chromeos/login/browser_chromeos.chrome_restart_request.o):../../chrome/browser/chromeos/login/chrome_restart_request.cc:chromeos::(anonymous namespace)::DeriveCommandLine(GURL const&, base::CommandLine const&, base::DictionaryValue const&, base::CommandLine*)::kForwardSwitches:error: undefined reference to 'switches::kRootLayerScrolls'
clang:error: linker command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.

Original issue's description:
> Add --root-layer-scrolls.
>
> BUG=417782
>
> Committed: https://crrev.com/2eeec6853a1579d09754acfa9961e4dc36aa9264
> Cr-Commit-Position: refs/heads/master@{#302588}

TBR=vollick@chromium.org,jam@chromium.org,skobes@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=417782

Review URL: https://codereview.chromium.org/695613005

Cr-Commit-Position: refs/heads/master@{#302590}

chrome/browser/chromeos/login/chrome_restart_request.cc

@@ -132,7 +132,6 @@ std::string DeriveCommandLine(const GURL& start_url,
     ::switches::kPpapiFlashVersion,
     ::switches::kPpapiInProcess,
     ::switches::kRendererStartupDialog,
-    ::switches::kRootLayerScrolls,
     ::switches::kEnableShareGroupAsyncTextureUpload,
     ::switches::kTabCaptureUpscaleQuality,
     ::switches::kTabCaptureDownscaleQuality,

content/browser/renderer_host/render_process_host_impl.cc

@@ -1175,7 +1175,6 @@ void RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer(
     switches::kRegisterPepperPlugins,
     switches::kRendererAssertTest,
     switches::kRendererStartupDialog,
-    switches::kRootLayerScrolls,
     switches::kShowPaintRects,
     switches::kSitePerProcess,
     switches::kStatsCollectionController,

content/public/common/content_switches.cc

@@ -715,9 +715,6 @@ const char kRendererProcessLimit[]          = "renderer-process-limit";
 // Causes the renderer process to display a dialog on launch.
 const char kRendererStartupDialog[]         = "renderer-startup-dialog";
 
-// Handles frame scrolls via the root RenderLayer instead of the FrameView.
-const char kRootLayerScrolls[]              = "root-layer-scrolls";
-
 // Causes the process to run as a sandbox IPC subprocess.
 const char kSandboxIPCProcess[]             = "sandbox-ipc";
 

content/public/common/content_switches.h

@@ -203,7 +203,6 @@ extern const char kRendererCmdPrefix[];
 CONTENT_EXPORT extern const char kRendererProcess[];
 CONTENT_EXPORT extern const char kRendererProcessLimit[];
 CONTENT_EXPORT extern const char kRendererStartupDialog[];
-extern const char kRootLayerScrolls[];
 extern const char kSandboxIPCProcess[];
 CONTENT_EXPORT extern const char kScrollEndEffect[];
 extern const char kShowPaintRects[];

content/renderer/render_view_impl.cc

@@ -751,8 +751,6 @@ void RenderViewImpl::Initialize(RenderViewImplParams* params) {
       ShouldUseTransitionCompositing(device_scale_factor_));
   webview()->settings()->setThreadedScrollingEnabled(
       !command_line.HasSwitch(switches::kDisableThreadedScrolling));
-  webview()->settings()->setRootLayerScrolls(
-      command_line.HasSwitch(switches::kRootLayerScrolls));
 
   ApplyWebPreferences(webkit_preferences_, webview());