Reverts "Bump minSdk to 19 for Android tests" (#47935)

Reverts #47686
Initiated by: zanderso
This change reverts the following previous change:
Original Description:
The latest Robolectric version, 4.11.x, removed the support for SDKs < 19 by following AndroidX strategy. Also following flutter/buildroot#750, and removing obsolete SDK checking in code to pass android_lint checking after bumping minSdk to 19 for testing target.

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

Author: auto-submit[bot]

shell/platform/android/AndroidManifest.xml

@@ -5,7 +5,7 @@
  -->
 <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="io.flutter.app" android:versionCode="1" android:versionName="0.0.1">
 
-    <uses-sdk android:minSdkVersion="19" android:targetSdkVersion="34" />
+    <uses-sdk android:minSdkVersion="16" android:targetSdkVersion="34" />
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
     <uses-feature android:name="android.hardware.sensor.accelerometer" android:required="true" />

shell/platform/android/io/flutter/embedding/android/AndroidTouchProcessor.java

@@ -198,7 +198,9 @@ public boolean onTouchEvent(@NonNull MotionEvent event, @NonNull Matrix transfor
   public boolean onGenericMotionEvent(@NonNull MotionEvent event, @NonNull Context context) {
     // Method isFromSource is only available in API 18+ (Jelly Bean MR2)
     // Mouse hover support is not implemented for API < 18.
-    boolean isPointerEvent = event.isFromSource(InputDevice.SOURCE_CLASS_POINTER);
+    boolean isPointerEvent =
+        Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2
+            && event.isFromSource(InputDevice.SOURCE_CLASS_POINTER);
     boolean isMovementEvent =
         (event.getActionMasked() == MotionEvent.ACTION_HOVER_MOVE
             || event.getActionMasked() == MotionEvent.ACTION_SCROLL);

shell/platform/android/io/flutter/embedding/android/FlutterFragment.java

@@ -8,6 +8,7 @@
 import android.content.ComponentCallbacks2;
 import android.content.Context;
 import android.content.Intent;
+import android.os.Build;
 import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -171,14 +172,16 @@ public class FlutterFragment extends Fragment
 
   @RequiresApi(18)
   private final OnWindowFocusChangeListener onWindowFocusChangeListener =
-      new OnWindowFocusChangeListener() {
-        @Override
-        public void onWindowFocusChanged(boolean hasFocus) {
-          if (stillAttachedForEvent("onWindowFocusChanged")) {
-            delegate.onWindowFocusChanged(hasFocus);
+      Build.VERSION.SDK_INT >= 18
+          ? new OnWindowFocusChangeListener() {
+            @Override
+            public void onWindowFocusChanged(boolean hasFocus) {
+              if (stillAttachedForEvent("onWindowFocusChanged")) {
+                delegate.onWindowFocusChanged(hasFocus);
+              }
+            }
           }
-        }
-      };
+          : null;
 
   /**
    * Creates a {@code FlutterFragment} with a default configuration.
@@ -1125,16 +1128,20 @@ public void onStop() {
   @Override
   public void onViewCreated(View view, Bundle savedInstanceState) {
     super.onViewCreated(view, savedInstanceState);
-    view.getViewTreeObserver().addOnWindowFocusChangeListener(onWindowFocusChangeListener);
+    if (Build.VERSION.SDK_INT >= 18) {
+      view.getViewTreeObserver().addOnWindowFocusChangeListener(onWindowFocusChangeListener);
+    }
   }
 
   @Override
   public void onDestroyView() {
     super.onDestroyView();
-    // onWindowFocusChangeListener is API 18+ only.
-    requireView()
-        .getViewTreeObserver()
-        .removeOnWindowFocusChangeListener(onWindowFocusChangeListener);
+    if (Build.VERSION.SDK_INT >= 18) {
+      // onWindowFocusChangeListener is API 18+ only.
+      requireView()
+          .getViewTreeObserver()
+          .removeOnWindowFocusChangeListener(onWindowFocusChangeListener);
+    }
     if (stillAttachedForEvent("onDestroyView")) {
       delegate.onDestroyView();
     }

shell/platform/android/io/flutter/embedding/android/FlutterImageView.java

@@ -39,6 +39,7 @@
  * an {@link android.media.Image} and renders it to the {@link android.graphics.Canvas} in {@code
  * onDraw}.
  */
+@TargetApi(19)
 public class FlutterImageView extends View implements RenderSurface {
   private static final String TAG = "FlutterImageView";
 
@@ -98,6 +99,7 @@ private static void logW(String format, Object... args) {
     Log.w(TAG, String.format(Locale.US, format, args));
   }
 
+  @TargetApi(19)
   @SuppressLint("WrongConstant") // RGBA_8888 is a valid constant.
   @NonNull
   private static ImageReader createImageReader(int width, int height) {
@@ -192,6 +194,7 @@ public void resume() {
    * Acquires the next image to be drawn to the {@link android.graphics.Canvas}. Returns true if
    * there's an image available in the queue.
    */
+  @TargetApi(19)
   public boolean acquireLatestImage() {
     if (!isAttachedToFlutterRenderer) {
       return false;

shell/platform/android/io/flutter/embedding/android/FlutterView.java

@@ -290,6 +290,7 @@ public FlutterView(@NonNull Context context, @NonNull FlutterTextureView flutter
    * <p>{@code FlutterView} requires an {@code Activity} instead of a generic {@code Context} to be
    * compatible with {@link PlatformViewsController}.
    */
+  @TargetApi(19)
   public FlutterView(@NonNull Context context, @NonNull FlutterImageView flutterImageView) {
     this(context, null, flutterImageView);
   }
@@ -356,6 +357,7 @@ private FlutterView(
     init();
   }
 
+  @TargetApi(19)
   private FlutterView(
       @NonNull Context context,
       @Nullable AttributeSet attrs,

shell/platform/android/io/flutter/embedding/engine/loader/FlutterLoader.java

@@ -16,6 +16,7 @@
 import android.os.Looper;
 import android.os.SystemClock;
 import android.util.DisplayMetrics;
+import android.view.WindowManager;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import io.flutter.BuildConfig;
@@ -169,9 +170,17 @@ public void startInitialization(@NonNull Context applicationContext, @NonNull Se
       flutterApplicationInfo = ApplicationInfoLoader.load(appContext);
 
       VsyncWaiter waiter;
-      final DisplayManager dm =
-          (DisplayManager) appContext.getSystemService(Context.DISPLAY_SERVICE);
-      waiter = VsyncWaiter.getInstance(dm, flutterJNI);
+      if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1 /* 17 */) {
+        final DisplayManager dm =
+            (DisplayManager) appContext.getSystemService(Context.DISPLAY_SERVICE);
+        waiter = VsyncWaiter.getInstance(dm, flutterJNI);
+      } else {
+        float fps =
+            ((WindowManager) appContext.getSystemService(Context.WINDOW_SERVICE))
+                .getDefaultDisplay()
+                .getRefreshRate();
+        waiter = VsyncWaiter.getInstance(fps, flutterJNI);
+      }
       waiter.init();
 
       // Use a background thread for initialization tasks that require disk access.

shell/platform/android/io/flutter/embedding/engine/mutatorsstack/FlutterMutatorView.java

@@ -3,6 +3,7 @@
 import static android.view.View.OnFocusChangeListener;
 
 import android.annotation.SuppressLint;
+import android.annotation.TargetApi;
 import android.content.Context;
 import android.graphics.Canvas;
 import android.graphics.Matrix;
@@ -22,6 +23,7 @@
  * A view that applies the {@link io.flutter.embedding.engine.mutatorsstack.FlutterMutatorsStack} to
  * its children.
  */
+@TargetApi(19)
 public class FlutterMutatorView extends FrameLayout {
   private FlutterMutatorsStack mutatorsStack;
   private float screenDensity;

shell/platform/android/io/flutter/embedding/engine/renderer/FlutterRenderer.java

@@ -355,6 +355,7 @@ public long id() {
     }
 
     @Override
+    @TargetApi(19)
     public void release() {
       if (released) {
         return;
@@ -368,6 +369,7 @@ public void release() {
     }
 
     @Override
+    @TargetApi(19)
     public void pushImage(Image image) {
       if (released) {
         return;
@@ -431,6 +433,7 @@ public Image acquireLatestImage() {
     }
 
     @Override
+    @TargetApi(19)
     protected void finalize() throws Throwable {
       try {
         if (released) {

shell/platform/android/io/flutter/plugin/localization/LocalizationPlugin.java

@@ -7,6 +7,7 @@
 import android.annotation.SuppressLint;
 import android.content.Context;
 import android.content.res.Configuration;
+import android.content.res.Resources;
 import android.os.Build;
 import android.os.LocaleList;
 import androidx.annotation.NonNull;
@@ -39,9 +40,18 @@ public String getStringResource(@NonNull String key, @Nullable String localeStri
             Locale locale = localeFromString(localeString);
 
             // setLocale and createConfigurationContext is only available on API >= 17
-            Configuration config = new Configuration(context.getResources().getConfiguration());
-            config.setLocale(locale);
-            localContext = context.createConfigurationContext(config);
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
+              Configuration config = new Configuration(context.getResources().getConfiguration());
+              config.setLocale(locale);
+              localContext = context.createConfigurationContext(config);
+            } else {
+              // In API < 17, we have to update the locale in Configuration.
+              Resources resources = context.getResources();
+              Configuration config = resources.getConfiguration();
+              savedLocale = config.locale;
+              config.locale = locale;
+              resources.updateConfiguration(config, null);
+            }
           }
 
           String packageName = context.getPackageName();
@@ -51,6 +61,14 @@ public String getStringResource(@NonNull String key, @Nullable String localeStri
             stringToReturn = localContext.getResources().getString(resId);
           }
 
+          // In API < 17, we had to restore the original locale after using.
+          if (localeString != null && Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR1) {
+            Resources resources = context.getResources();
+            Configuration config = resources.getConfiguration();
+            config.locale = savedLocale;
+            resources.updateConfiguration(config, null);
+          }
+
           return stringToReturn;
         }
       };

shell/platform/android/io/flutter/plugin/platform/PlatformPlugin.java

@@ -282,7 +282,8 @@ private void setSystemChromeEnabledSystemUIMode(PlatformChannel.SystemUiMode sys
               | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
               | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
               | View.SYSTEM_UI_FLAG_FULLSCREEN;
-    } else if (systemUiMode == PlatformChannel.SystemUiMode.IMMERSIVE) {
+    } else if (systemUiMode == PlatformChannel.SystemUiMode.IMMERSIVE
+        && Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
       // IMMERSIVE
       // Available starting at 19
       // Should not show overlays, swipe from edges to reveal overlays, needs onChange callback
@@ -297,7 +298,8 @@ private void setSystemChromeEnabledSystemUIMode(PlatformChannel.SystemUiMode sys
               | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
               | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
               | View.SYSTEM_UI_FLAG_FULLSCREEN;
-    } else if (systemUiMode == PlatformChannel.SystemUiMode.IMMERSIVE_STICKY) {
+    } else if (systemUiMode == PlatformChannel.SystemUiMode.IMMERSIVE_STICKY
+        && Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
       // STICKY IMMERSIVE
       // Available starting at 19
       // Should not show overlays, swipe from edges to reveal overlays. The app will also receive
@@ -344,7 +346,7 @@ private void setSystemChromeEnabledSystemUIOverlays(
     // The SYSTEM_UI_FLAG_IMMERSIVE_STICKY flag was introduced in API 19, so we
     // apply it
     // if desired, and if the current Android version is 19 or greater.
-    if (overlaysToShow.size() == 0) {
+    if (overlaysToShow.size() == 0 && Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
       enabledOverlays |= View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY;
     }