[components] Close https://github.com/mozilla-mobile/android-components/issues/8040: Move ImageLoader to support-base

The `ImageLoader` API is public and we should have it in a better place.

mobile/android/android-components/components/concept/base/build.gradle

@@ -27,6 +27,7 @@ android {
 dependencies {
     implementation Dependencies.kotlin_stdlib
     implementation Dependencies.kotlin_coroutines
+    implementation Dependencies.androidx_annotation
 
     testImplementation Dependencies.androidx_test_junit
     testImplementation Dependencies.testing_robolectric

mobile/android/android-components/components/concept/base/src/main/java/mozilla/components/concept/base/images/ImageLoader.kt

@@ -0,0 +1,32 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package mozilla.components.concept.base.images
+
+import android.graphics.drawable.Drawable
+import android.widget.ImageView
+import androidx.annotation.MainThread
+
+/**
+ * A loader that can load an image from an ID directly into an [ImageView].
+ */
+interface ImageLoader {
+
+    /**
+     * Loads an image asynchronously and then displays it in the [ImageView].
+     * If the view is detached from the window before loading is completed, then loading is cancelled.
+     *
+     * @param view [ImageView] to load the image into.
+     * @param request [ImageLoadRequest] Load image for this given request.
+     * @param placeholder [Drawable] to display while image is loading.
+     * @param error [Drawable] to display if loading fails.
+     */
+    @MainThread
+    fun loadIntoView(
+        view: ImageView,
+        request: ImageLoadRequest,
+        placeholder: Drawable? = null,
+        error: Drawable? = null
+    )
+}

mobile/android/android-components/components/concept/base/src/main/java/mozilla/components/concept/base/images/ImageRequest.kt

@@ -0,0 +1,23 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package mozilla.components.concept.base.images
+
+import androidx.annotation.Px
+
+/**
+ * A request to save an image. This is an alias for the id of the image.
+ */
+typealias ImageSaveRequest = String
+
+/**
+ * A request to load an image.
+ *
+ * @property id The id of the image to retrieve.
+ * @property size The preferred size of the image that should be loaded in pixels.
+ */
+data class ImageLoadRequest(
+    val id: String,
+    @Px val size: Int
+)