ui: Read custom recovery UI values via system property.

The matching change to build system now writes these values as build
properties for recovery image. This allows us dropping the dependency on
Android.mk (as well as having more flexibility to do UI customization).

Also rename a few constant names, as the naming doesn't fully follow the
style guide (which reads "whose value is fixed for the duration of the
program").

Bug: 110380063
Test: Build and flash recovery image on taimen, which uses custom margin
      height. Check the UI and choose `Run graphics test`.
Change-Id: I2c50326123639cb36022f51b62cdeed925d77ba7

wear_ui.cpp

@@ -25,17 +25,22 @@
 #include <android-base/strings.h>
 #include <minui/minui.h>
 
+constexpr int kDefaultProgressBarBaseline = 259;
+constexpr int kDefaultMenuUnusableRows = 9;
+
 WearRecoveryUI::WearRecoveryUI()
     : ScreenRecoveryUI(true),
-      kProgressBarBaseline(RECOVERY_UI_PROGRESS_BAR_BASELINE),
-      kMenuUnusableRows(RECOVERY_UI_MENU_UNUSABLE_ROWS) {
-  // TODO: kMenuUnusableRows should be computed based on the lines in draw_screen_locked().
+      progress_bar_baseline_(android::base::GetIntProperty("ro.recovery.ui.progress_bar_baseline",
+                                                           kDefaultProgressBarBaseline)),
+      menu_unusable_rows_(android::base::GetIntProperty("ro.recovery.ui.menu_unusable_rows",
+                                                        kDefaultMenuUnusableRows)) {
+  // TODO: menu_unusable_rows_ should be computed based on the lines in draw_screen_locked().
 
   touch_screen_allowed_ = true;
 }
 
 int WearRecoveryUI::GetProgressBaseline() const {
-  return kProgressBarBaseline;
+  return progress_bar_baseline_;
 }
 
 // Draw background frame on the screen.  Does not flip pages.
@@ -94,7 +99,7 @@ void WearRecoveryUI::StartMenu(const std::vector<std::string>& headers,
                                const std::vector<std::string>& items, size_t initial_selection) {
   std::lock_guard<std::mutex> lg(updateMutex);
   if (text_rows_ > 0 && text_cols_ > 0) {
-    menu_ = std::make_unique<Menu>(scrollable_menu_, text_rows_ - kMenuUnusableRows - 1,
+    menu_ = std::make_unique<Menu>(scrollable_menu_, text_rows_ - menu_unusable_rows_ - 1,
                                    text_cols_ - 1, headers, items, initial_selection);
     update_screen_locked();
   }