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

ui/base/material_design/material_design_controller.h

Index: ui/base/material_design/material_design_controller.h
diff --git a/ui/base/material_design/material_design_controller.h b/ui/base/material_design/material_design_controller.h
index 46363f776b1a3622726865439f3f60def1e5db5c..5960f3ece1dea548c2a295f949df99234b6ec8bc 100644
--- a/ui/base/material_design/material_design_controller.h
+++ b/ui/base/material_design/material_design_controller.h
@@ -44,6 +44,11 @@ class UI_BASE_EXPORT MaterialDesignController {
   // Returns the per-platform default material design variant.
   static Mode DefaultMode();
 
+  // On Windows, this should be called during startup before anyone calls any of
+  // the functions above to declare whether we should default to Material mode.
+  // TODO(pkasting): Remove this as soon as MD is on by default.
+  static void SetWindowsShouldDefaultToMaterial(bool default_to_material);
+
  private:
   friend class test::MaterialDesignControllerTestAPI;
 
@@ -51,6 +56,9 @@ class UI_BASE_EXPORT MaterialDesignController {
   // reset the state back to a clean state during tear down.
   static bool is_mode_initialized_;
 
+  // True if on Windows we should default to Material mode.
+  static bool windows_should_default_to_material_;
+
   // The current Mode to be used by the system.
   static Mode mode_;