Remove "device scale factor" option from about flags page.

--force-device-scale-factor is kept for dev purpose.

BUG=None

Review URL: https://codereview.chromium.org/580083004

Cr-Commit-Position: refs/heads/master@{#295673}

chrome/app/generated_resources.grd

@@ -5584,20 +5584,6 @@ Keep your key file in a safe place. You will need it to create new versions of y
       <message name="IDS_FLAGS_DEBUG_SHORTCUTS_DESCRIPTION" desc="Description of the 'Debugging keyboard shortcuts' lab.">
         Enables additional keyboard shortcuts that are useful for debugging Chromium.
       </message>
-      <if expr="chromeos or is_win or is_linux">
-        <message name="IDS_FLAGS_FORCE_DEVICE_SCALE_FACTOR_NAME" desc="Name of the 'Force device scale factor' lab.">
-          Overrides the device scale factor on the device.
-        </message>
-        <message name="IDS_FLAGS_FORCE_DEVICE_SCALE_FACTOR_DESCRIPTION" desc="Description of the 'Force device scale factor' lab.">
-          Overrides the device display density to force the use of high DPI mode and assets.
-        </message>
-        <message name="IDS_DEVICE_SCALE_FACTOR_1_1" desc=""> 1.1 </message>
-        <message name="IDS_DEVICE_SCALE_FACTOR_1_2" desc=""> 1.2 </message>
-        <message name="IDS_DEVICE_SCALE_FACTOR_1_25" desc=""> 1.25 </message>
-        <message name="IDS_DEVICE_SCALE_FACTOR_1_3" desc=""> 1.3 </message>
-        <message name="IDS_DEVICE_SCALE_FACTOR_1_4" desc=""> 1.4 </message>
-        <message name="IDS_DEVICE_SCALE_FACTOR_2" desc=""> 2.0 </message>
-      </if>
       <message name="IDS_FLAGS_IGNORE_GPU_BLACKLIST_NAME" desc="Name of the 'Ignore GPU blacklist' lab.">
         Override software rendering list
       </message>

chrome/browser/about_flags.cc

@@ -181,17 +181,6 @@ const Experiment::Choice kOverscrollHistoryNavigationChoices[] = {
     "2" }
 };
 #endif
-#if defined(OS_CHROMEOS) || defined(OS_WIN) || defined(OS_LINUX)
-const Experiment::Choice kDeviceScaleFactorChoices[] = {
-  { IDS_GENERIC_EXPERIMENT_CHOICE_DEFAULT, "", ""},
-  { IDS_DEVICE_SCALE_FACTOR_1_1, switches::kForceDeviceScaleFactor, "1.1"},
-  { IDS_DEVICE_SCALE_FACTOR_1_2, switches::kForceDeviceScaleFactor, "1.2"},
-  { IDS_DEVICE_SCALE_FACTOR_1_25, switches::kForceDeviceScaleFactor, "1.25"},
-  { IDS_DEVICE_SCALE_FACTOR_1_3, switches::kForceDeviceScaleFactor, "1.3"},
-  { IDS_DEVICE_SCALE_FACTOR_1_4, switches::kForceDeviceScaleFactor, "1.4"},
-  { IDS_DEVICE_SCALE_FACTOR_2, switches::kForceDeviceScaleFactor, "2"},
-};
-#endif
 
 #if !defined(DISABLE_NACL)
 const Experiment::Choice kNaClDebugMaskChoices[] = {
@@ -928,15 +917,6 @@ const Experiment kExperiments[] = {
     SINGLE_VALUE_TYPE_AND_VALUE(switches::kAllowNaClSocketAPI, "*")
   },
 #endif
-#if defined(OS_CHROMEOS) || defined(OS_WIN) || defined(OS_LINUX)
-  {
-    "force-device-scale-factor",
-    IDS_FLAGS_FORCE_DEVICE_SCALE_FACTOR_NAME,
-    IDS_FLAGS_FORCE_DEVICE_SCALE_FACTOR_DESCRIPTION,
-    kOsLinux | kOsWin | kOsCrOS,
-    MULTI_VALUE_TYPE(kDeviceScaleFactorChoices)
-  },
-#endif
 #if defined(OS_CHROMEOS)
   {
     "allow-touchpad-three-finger-click",