[iOS] Replace background image with a uniform color.

ios/chrome/browser/ui/background_generator.mm

Index: ios/chrome/browser/ui/background_generator.mm
diff --git a/ios/chrome/browser/ui/background_generator.mm b/ios/chrome/browser/ui/background_generator.mm
index d21b44da54114be93c19e45c8ab642c44366e5b5..517ef42528893c92b4e17efd0ef4da130521bcb3 100644
--- a/ios/chrome/browser/ui/background_generator.mm
+++ b/ios/chrome/browser/ui/background_generator.mm
@@ -11,6 +11,7 @@
 #include "base/mac/foundation_util.h"
 #include "base/mac/scoped_cftyperef.h"
 #import "ios/chrome/browser/ui/ui_util.h"
+#import "ios/third_party/material_components_ios/src/components/Palettes/src/MaterialPalettes.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
@@ -51,10 +52,5 @@ UIImage* GetRadialGradient(CGRect backgroundRect,
 }
 
 void InstallBackgroundInView(UIView* view) {
-  UIImageView* imageView = [[UIImageView alloc] initWithFrame:view.bounds];
-  imageView.image = [UIImage imageNamed:@"stack_view_background_noise.jpg"];
-  imageView.contentMode = UIViewContentModeScaleAspectFill;
-  imageView.autoresizingMask =
-      UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
-  [view insertSubview:imageView atIndex:0];
+  [view setBackgroundColor:[[MDCPalette greyPalette] tint900]];
 }