[cr140][Android] Fixed color of search your downloads textbox (#30856)

* [cr140][Android] Fixed color of search your downloads textbox

The color `@color/toolbar_text_box_bg_color` was used which does not
depend on Brave's color accent.

Resolves https://github.com/brave/brave-browser/issues/48702

Chromium change:
https://source.chromium.org/chromium/chromium/src/+/e2ecd7051160bea613211a3943155a09b1ad62cc

	Implement new Download page UI for LFF devices

	Implements the new UI for the Download Manager page on large-screen
	devices based on the approved UX spec, http://shortn/_9stIgUxL1u.

	UI behavior after changed: http://shortn/_FOLyyoTdOG

	Bug: 422042079
	Test: chrome://downloads should match UI team's design on LFF device
	Change-Id: Ieb77fcd38d86fd023a149c8186fc1de84819bb60
	Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6733725

android/java/apk_for_test.flags

@@ -1021,3 +1021,11 @@
 -keep class org.chromium.chrome.browser.toolbar.adaptive.AdaptiveToolbarPrefs {
     *** getCustomizationSetting(...);
 }
+
+-keep class org.chromium.chrome.browser.download.home.search.SearchBarCoordinator {
+    <init>(...);
+}
+
+-keep class org.chromium.chrome.browser.download.home.search.BraveSearchBarCoordinator {
+    <init>(...);
+}