Extract a base class from CommandLinePrefStore

Currently, CommandLinePrefStore (1) holds all the {switches,
preferences} maps in chrome, (2) applys the command line switches to
their corresponding preferences for the maps it holds.

This CL extracts the logic of applying simple command line switches to the
corresponding preferences in a base class, and rename the class in
chrome/ to ChromeCommandLinePrefStore. So that
ChromeCommandLinePrefStore will call the Apply*Switches methods in its
base class instead.

We made this change because we want to be able to delegate handling
Blimp command line switch to /blimp.

BUG=647848

Review-Url: https://codereview.chromium.org/2419733005
Cr-Commit-Position: refs/heads/master@{#425713}
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index e22b2d26..8410f09a 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -841,12 +841,12 @@
     "predictors/resource_prefetcher_manager.h",
     "prefs/browser_prefs.cc",
     "prefs/browser_prefs.h",
+    "prefs/chrome_command_line_pref_store.cc",
+    "prefs/chrome_command_line_pref_store.h",
     "prefs/chrome_pref_model_associator_client.cc",
     "prefs/chrome_pref_model_associator_client.h",
     "prefs/chrome_pref_service_factory.cc",
     "prefs/chrome_pref_service_factory.h",
-    "prefs/command_line_pref_store.cc",
-    "prefs/command_line_pref_store.h",
     "prefs/incognito_mode_prefs.cc",
     "prefs/incognito_mode_prefs.h",
     "prefs/origin_trial_prefs.cc",
@@ -1355,6 +1355,7 @@
     "//components/policy:generated",
     "//components/policy/core/browser",
     "//components/policy/proto",
+    "//components/prefs:prefs",
     "//components/previews/core",
     "//components/profile_metrics",
     "//components/proxy_config",