Change frame and inactive tab color to a custom #DEE1E6 instead of GoogleGrey200.

UX requested this minor change in advance of a user-study focused on getting direct usability feedback for the new UI changes.

Bug: 850981
Change-Id: I1a673fd16bcc1ed736eb35399839ec653a5fb51d
Reviewed-on: https://chromium-review.googlesource.com/1092793
Commit-Queue: Allen Bauer <kylixrd@chromium.org>
Reviewed-by: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565689}

chrome/browser/themes/theme_properties.cc

@@ -154,7 +154,7 @@ base::Optional<SkColor> MaybeGetDefaultColorForNewerMaterialUi(int id,
     case ThemeProperties::COLOR_FRAME:
     case ThemeProperties::COLOR_FRAME_INACTIVE:
     case ThemeProperties::COLOR_BACKGROUND_TAB:
-      return incognito ? gfx::kGoogleGrey900 : gfx::kGoogleGrey200;
+      return incognito ? gfx::kGoogleGrey900 : SkColorSetRGB(0xDE, 0xE1, 0xE6);
     case ThemeProperties::COLOR_TOOLBAR:
       return incognito ? SkColorSetRGB(0x32, 0x36, 0x39) : SK_ColorWHITE;