Flag rename for "Enable Compositor Threaded Scrollbar Scrolling".

This CL renames "Enable Compositor Threaded Scrollbar Scrolling" to
"Compositor Threaded Scrollbar Scrolling". The flag already has options
to enable/disable it. Hence the "Enable" part of the flag name can be
removed for improved readability.

Bug: 962715

Change-Id: If955ec074b2bd77b7b1a22f4102068950d4c2dff
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1598344Reviewed-by: Reilly Grant <reillyg@chromium.org>
Commit-Queue: Rahul Arakeri <arakeri@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#659288}

chrome/browser/about_flags.cc

@@ -3265,7 +3265,7 @@ const FeatureEntry kFeatureEntries[] = {
                                     kResamplingInputEventsFeatureVariations,
                                     "ResamplingScrollEvents")},
 
-    {"enable-compositor-threaded-scrollbar-scrolling",
+    {"compositor-threaded-scrollbar-scrolling",
      flag_descriptions::kCompositorThreadedScrollbarScrollingName,
      flag_descriptions::kCompositorThreadedScrollbarScrollingDescription,
      kOsAll,

chrome/browser/flag-metadata.json

@@ -390,6 +390,11 @@
     "owners": [ "ccameron" ],
     "expiry_milestone": 76
   },
+  {
+    "name": "compositor-threaded-scrollbar-scrolling",
+    "owners": [ "arakeri@microsoft.com" ],
+    "expiry_milestone": 80
+  },
   {
     "name": "contextual-search",
     "owners": [ "//chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/OWNERS" ],
@@ -1158,11 +1163,6 @@
     "owners": [ "ccameron" ],
     "expiry_milestone": 77
   },
-  {
-    "name": "enable-compositor-threaded-scrollbar-scrolling",
-    "owners": [ "arakeri@microsoft.com" ],
-    "expiry_milestone": 80
-  },
   {
     "name": "identity-disc",
     "owners": ["//chrome/android/java/src/org/chromium/chrome/browser/toolbar/OWNERS"],

chrome/browser/flag_descriptions.cc

@@ -736,7 +736,7 @@ const char kVizHitTestDescription[] =
     "with hit-test data computed from the CompositorFrame or the SurfaceLayer.";
 
 const char kCompositorThreadedScrollbarScrollingName[] =
-    "Enable compositor threaded scrollbar scrolling";
+    "Compositor threaded scrollbar scrolling";
 const char kCompositorThreadedScrollbarScrollingDescription[] =
     "Enables pointer-based scrollbar scrolling on the compositor thread "
     "instead of the main thread";