[NTP] Increase --logo-margin-bottom

Increase the bottom margin by 9px. This prevents shifting of page
contents in dark mode.

before: http://screen/AF6E8KpyjxM.png
after: http://screen/7RFWj2Qv87k.png

Bug: 983457
Change-Id: I70d5cf81d2650829d1bc3121e5fbeb251a6420eb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1699687
Commit-Queue: Kyle Milka <kmilka@chromium.org>
Reviewed-by: Kristi Park <kristipark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#677112}

chrome/browser/resources/local_ntp/doodles.js

@@ -394,7 +394,6 @@ doodles.showLogoOrDoodle = function(fromCache) {
       const isDarkModeEnabled =
           window.matchMedia('(prefers-color-scheme: dark)').matches;
       if (isDarkModeEnabled) {
-        document.body.style.setProperty('--logo-margin-bottom', '34px');
         $(doodles.IDS.LOGO_DOODLE_WRAPPER).style.backgroundColor =
             doodles.targetDoodle.metadata.darkBackgroundColor;
       }

chrome/browser/resources/local_ntp/local_ntp.css

@@ -17,7 +17,7 @@ html {
 
   --logo-height: 200px; /* Normal height of a doodle. */
   --logo-margin-top: 56px; /* Expected OGB height, so logo doesn't overlap. */
-  --logo-margin-bottom: 29px; /* Between logo and fakebox. */
+  --logo-margin-bottom: 38px; /* Between logo and fakebox. */
 
   /* Initial height determines the margin between the logo and the fakebox. If
    * the iframe height exceeds the normal --logo-height, the difference is

chrome/browser/ui/search/local_ntp_doodle_browsertest.cc

@@ -48,13 +48,10 @@ namespace {
 
 const char kCachedB64[] = "\161\247\041\171\337\276";  // b64decode("cached++")
 const char kFreshB64[] = "abc";                        // b64decode("YWJj")
-const int kFakeboxTopPx = 56 + 200 + 29;  // top margin + height + bottom margin
+const int kFakeboxTopPx = 56 + 200 + 38;  // top margin + height + bottom margin
 
 #if defined(OS_WIN) || defined(OS_MACOSX)
 const char kFreshDarkB64[] = "xyz";  // b64decode("eHl6");
-const int kDarkModeFakeboxTopPx =
-    56 + 200 + 29 +
-    5;  // top margin + height + bottom margin + extra spacing in dark mode
 #endif
 
 // A base64 encoding of a tiny but valid gif file.
@@ -1495,8 +1492,7 @@ IN_PROC_BROWSER_TEST_F(LocalNTPDarkModeDoodleTest,
   ui_test_utils::NavigateToURL(browser(), GURL(chrome::kChromeUINewTabURL));
 
   WaitForFadeIn(active_tab, "logo-doodle");
-  EXPECT_THAT(GetDimension(active_tab, "fakebox", "top"),
-              Eq(kDarkModeFakeboxTopPx));
+  EXPECT_THAT(GetDimension(active_tab, "fakebox", "top"), Eq(kFakeboxTopPx));
   EXPECT_THAT(GetComputedOpacity(active_tab, "logo-default"), Eq(0.0));
   EXPECT_THAT(GetComputedOpacity(active_tab, "logo-doodle"), Eq(1.0));
   EXPECT_THAT(GetComputedDisplay(active_tab, "logo-doodle-container"),
@@ -1587,8 +1583,7 @@ IN_PROC_BROWSER_TEST_F(LocalNTPDarkModeDoodleTest,
 
   WaitForLogoSwap(active_tab, "logo-doodle");
   EXPECT_TRUE(GetIsDarkModeApplied(active_tab));
-  EXPECT_THAT(GetDimension(active_tab, "fakebox", "top"),
-              Eq(kDarkModeFakeboxTopPx));
+  EXPECT_THAT(GetDimension(active_tab, "fakebox", "top"), Eq(kFakeboxTopPx));
   EXPECT_THAT(GetComputedOpacity(active_tab, "logo-default"), Eq(0.0));
   EXPECT_THAT(GetComputedOpacity(active_tab, "logo-doodle"), Eq(1.0));
   EXPECT_THAT(GetComputedDisplay(active_tab, "logo-doodle-container"),