Enable MD by default on Windows for Canary/Dev and local builds.

ui/base/material_design/material_design_controller.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <string>
 
 #include "base/command_line.h"
 #include "base/logging.h"
+#include "base/metrics/field_trial.h"
 #include "base/trace_event/trace_event.h"
 #include "ui/base/material_design/material_design_controller.h"
 #include "ui/base/ui_base_switches.h"
 
 #if defined(OS_CHROMEOS)
 #include "ui/base/touch/touch_device.h"
 #include "ui/events/devices/device_data_manager.h"
 
 #if defined(USE_OZONE)
 #include <fcntl.h>
 
 #include "base/files/file_enumerator.h"
 #include "ui/events/ozone/evdev/event_device_info.h"
 #endif  // defined(USE_OZONE)
 
 #endif  // defined(OS_CHROMEOS)
 
 namespace ui {
 
+// static
 bool MaterialDesignController::is_mode_initialized_ = false;
-
+bool MaterialDesignController::windows_should_default_to_material_ = false;
 MaterialDesignController::Mode MaterialDesignController::mode_ =
     MaterialDesignController::NON_MATERIAL;
 
 bool MaterialDesignController::include_secondary_ui_ = false;
 
 // static
 void MaterialDesignController::Initialize() {
   TRACE_EVENT0("startup", "MaterialDesignController::InitializeMode");
   CHECK(!is_mode_initialized_);
 #if !defined(ENABLE_TOPCHROME_MD)
@@ skipping 34 matching lines @@
   return GetMode() == MATERIAL_NORMAL || GetMode() == MATERIAL_HYBRID;
 }
 
 // static
 bool MaterialDesignController::IsSecondaryUiMaterial() {
   return IsModeMaterial() && include_secondary_ui_;
 }
 
 // static
 MaterialDesignController::Mode MaterialDesignController::DefaultMode() {
+  // The field trial value, if any, overrides the platform defaults below.
+  constexpr char kMaterialDesignModeFieldTrialName[] = "MaterialDesignMode";
+  constexpr char kNonMaterialGroupName[] = "NonMaterial";
+  constexpr char kMaterialNormalGroupName[] = "MaterialNormal";
+  constexpr char kMaterialHybridGroupName[] = "MaterialHybrid";
+  const std::string group =
+      base::FieldTrialList::FindFullName(kMaterialDesignModeFieldTrialName);
+  if (group == kNonMaterialGroupName)
+    return NON_MATERIAL;
+  if (group == kMaterialNormalGroupName)
+    return MATERIAL_NORMAL;
+  if (group == kMaterialHybridGroupName)
+    return MATERIAL_HYBRID;
+
+  // No recognized field trial group; fall back to per-platform defaults.
 #if defined(OS_CHROMEOS)
   if (DeviceDataManager::HasInstance() &&
       DeviceDataManager::GetInstance()->device_lists_complete()) {
     return GetTouchScreensAvailability() == TouchScreensAvailability::ENABLED
                ? MATERIAL_HYBRID
                : MATERIAL_NORMAL;
   }
 
 #if defined(USE_OZONE)
   base::FileEnumerator file_enum(
       base::FilePath(FILE_PATH_LITERAL("/dev/input")), false,
       base::FileEnumerator::FILES, FILE_PATH_LITERAL("event*[0-9]"));
   for (base::FilePath path = file_enum.Next(); !path.empty();
        path = file_enum.Next()) {
     EventDeviceInfo devinfo;
     int fd = open(path.value().c_str(), O_RDWR | O_NONBLOCK | O_CLOEXEC);
     if (fd >= 0) {
       if (devinfo.Initialize(fd, path) && devinfo.HasTouchscreen()) {
         close(fd);
         return MATERIAL_HYBRID;
       }
       close(fd);
     }
   }
 #endif  // defined(USE_OZONE)
   return MATERIAL_NORMAL;
 #elif defined(OS_LINUX)
   return MATERIAL_NORMAL;
+#elif defined(OS_WIN)
+  return windows_should_default_to_material_ ? MATERIAL_NORMAL : NON_MATERIAL;
 #else
   return NON_MATERIAL;
 #endif  // defined(OS_CHROMEOS)
 }
 
 // static
+void MaterialDesignController::SetWindowsShouldDefaultToMaterial(
+    bool default_to_material) {
+  windows_should_default_to_material_ = default_to_material;
+}
+
+// static
 void MaterialDesignController::Uninitialize() {
   is_mode_initialized_ = false;
 }
 
 // static
 void MaterialDesignController::SetMode(MaterialDesignController::Mode mode) {
   mode_ = mode;
   is_mode_initialized_ = true;
 }
 
 }  // namespace ui