[NTP] Enable scrolling for the voice search dialog

Use absolute instead of fixed positioning for the voice search dialog in
order to enable scrolling.

Bug: 865831
Change-Id: I43505223301c77e6ac8502a1f505a0d4d0def6ab
Reviewed-on: https://chromium-review.googlesource.com/c/1416951
Reviewed-by: Kyle Milka <kmilka@chromium.org>
Commit-Queue: Kristi Park <kristipark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#623812}
diff --git a/chrome/browser/resources/local_ntp/local_ntp.css b/chrome/browser/resources/local_ntp/local_ntp.css
index a8678f8f..242f282 100644
--- a/chrome/browser/resources/local_ntp/local_ntp.css
+++ b/chrome/browser/resources/local_ntp/local_ntp.css
@@ -464,6 +464,7 @@
 
 #mv-single {
   border: none;
+  display: block;
   height: 100%;
   width: 100%;
 }
diff --git a/chrome/browser/resources/local_ntp/voice.css b/chrome/browser/resources/local_ntp/voice.css
index 8a33a16..4d97344 100644
--- a/chrome/browser/resources/local_ntp/voice.css
+++ b/chrome/browser/resources/local_ntp/voice.css
@@ -41,22 +41,28 @@
 .overlay-dialog {
   background: transparent;
   border: none;
+  height: 100%;
+  left: 0;
+  margin: auto;
+  padding: 0;
+  position: absolute;
+  right: 0;
+  top: 0;
+  width: 100%;
+}
+
+.overlay-dialog::backdrop {
+  background-color: white;
 }
 
 /* The background element. */
 .overlay,
 .overlay-hidden {
   background: white;
-  height: 100%;
-  left: 0;
   opacity: 0;
-  overflow: hidden;
-  position: fixed;
   text-align: left;
-  top: 0;
   transition: visibility 0s linear 218ms, background-color 218ms;
   visibility: hidden;
-  width: 100%;
   z-index: 10000;
 }
 
@@ -77,10 +83,11 @@
   margin: 15px;
   opacity: .54;
   padding: 0;
-  position: absolute;
+  position: fixed;
   right: 0;
   top: 0;
   width: 15px;
+  z-index: 1;
 }
 
 html[dir=rtl] .close-button {
@@ -157,7 +164,7 @@
   opacity: 0;
   pointer-events: none;
   position: absolute;
-  transition-delay: 0;
+  transition-delay: 0s;
 }
 
 /* Button state when speech recognition is active. */
@@ -165,7 +172,7 @@
   opacity: 1;
   pointer-events: auto;
   position: absolute;
-  transition-delay: 0;
+  transition-delay: 0s;
 }
 
 /* Button state when speech input is being received by the microphone. */