[NTP] Improve readability of text on custom backgrounds.

Applies a 20% black overlay on a custom background image, uses white font text,
and a white settings icon.

Bug: 850312, 851285
Cq-Include-Trybots: luci.chromium.try:closure_compilation
Change-Id: Ia6cab65d08bc6e54a42b78732b42b9cd4d8dc549
Reviewed-on: https://chromium-review.googlesource.com/1098557
Commit-Queue: Ramya Nagarajan <ramyan@chromium.org>
Reviewed-by: ccameron <ccameron@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568088}

chrome/browser/resources/local_ntp/custom_backgrounds.css

@@ -26,6 +26,11 @@
   width: 100%;
 }
 
+.non-white-bg #edit-bg-gear {
+  background: url(../../../../ui/webui/resources/images/icon_settings_white.svg) no-repeat center;
+  background-size: 16px 16px;
+}
+
 #edit-bg-overlay {
   display: none;
   height: 100%;

chrome/browser/resources/local_ntp/local_ntp.js

@@ -180,6 +180,8 @@ var LOG_TYPE = {
  */
 var WHITE_BACKGROUND_COLORS = ['rgba(255,255,255,1)', 'rgba(0,0,0,0)'];
 
+const CUSTOM_BACKGROUND_OVERLAY =
+    'linear-gradient(rgba(0, 0, 0, 0.2), rgba(0, 0, 0, 0.2))';
 
 /**
  * Enum for keycodes.
@@ -300,8 +302,13 @@ function renderTheme() {
   updateThemeAttribution(info.attributionUrl, info.imageHorizontalAlignment);
   setCustomThemeStyle(info);
 
+  if (info.customBackgroundConfigured) {
+    var imageWithOverlay =
+        [CUSTOM_BACKGROUND_OVERLAY, info.imageUrl].join(',').trim();
+    document.body.style.setProperty('background-image', imageWithOverlay);
+  }
   $(customBackgrounds.IDS.RESTORE_DEFAULT).hidden =
-      !(info.imageUrl && info.imageUrl.length > 0);
+      !info.customBackgroundConfigured;
 
   if (configData.isGooglePage) {
     $('edit-bg').hidden =

chrome/common/search/instant_types.cc

@@ -11,6 +11,9 @@ RGBAColor::RGBAColor()
       a(0) {
 }
 
+RGBAColor::RGBAColor(uint8_t r, uint8_t g, uint8_t b, uint8_t a)
+    : r(r), g(g), b(b), a(a) {}
+
 RGBAColor::~RGBAColor() {
 }
 

chrome/common/search/instant_types.h

@@ -44,6 +44,7 @@ enum ThemeBackgroundImageTiling {
 // The RGBA color components for the text and links of the theme.
 struct RGBAColor {
   RGBAColor();
+  RGBAColor(uint8_t r, uint8_t g, uint8_t b, uint8_t a);
   ~RGBAColor();
 
   bool operator==(const RGBAColor& rhs) const;

chrome/renderer/searchbox/searchbox_extension.cc

@@ -342,6 +342,11 @@ v8::Local<v8::Object> GenerateThemeBackgroundInfo(
 
   if (theme_info.using_default_theme &&
       !theme_info.custom_background_url.is_empty()) {
+    builder.Set("alternateLogo", true);
+    RGBAColor whiteTextRgba = RGBAColor{255, 255, 255, 255};
+    builder.Set("textColorRgba",
+                internal::RGBAColorToArray(isolate, whiteTextRgba));
+    builder.Set("customBackgroundConfigured", true);
     builder.Set("imageUrl",
                 "url('" + theme_info.custom_background_url.spec() + "')");
     builder.Set("imageTiling", std::string(kCSSBackgroundRepeatNo));

ui/webui/resources/images/icon_settings_white.svg

+<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="#e8eaed" preserveAspectRatio="xMidYMid meet"><path class="gear-icon" d="M19.43 12.98c.04-.32.07-.64.07-.98s-.03-.66-.07-.98l2.11-1.65c.19-.15.24-.42.12-.64l-2-3.46c-.12-.22-.39-.3-.61-.22l-2.49 1c-.52-.4-1.08-.73-1.69-.98l-.38-2.65C14.46 2.18 14.25 2 14 2h-4c-.25 0-.46.18-.49.42l-.38 2.65c-.61.25-1.17.59-1.69.98l-2.49-1c-.23-.09-.49 0-.61.22l-2 3.46c-.13.22-.07.49.12.64l2.11 1.65c-.04.32-.07.65-.07.98s.03.66.07.98l-2.11 1.65c-.19.15-.24.42-.12.64l2 3.46c.12.22.39.3.61.22l2.49-1c.52.4 1.08.73 1.69.98l.38 2.65c.03.24.24.42.49.42h4c.25 0 .46-.18.49-.42l.38-2.65c.61-.25 1.17-.59 1.69-.98l2.49 1c.23.09.49 0 .61-.22l2-3.46c.12-.22.07-.49-.12-.64l-2.11-1.65zM12 15.5c-1.93 0-3.5-1.57-3.5-3.5s1.57-3.5 3.5-3.5 3.5 1.57 3.5 3.5-1.57 3.5-3.5 3.5z"></path></svg>