[firebase_ml_custom] New firebase_ml_custom plugin to download custom models from Firebase (#3122)

* [firebase_ml_custom] Add support for using custom ML models.

Author: PolinaGo

packages/firebase_ml_custom/.gitignore

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+.DS_Store
+.dart_tool/
+
+.packages
+.pub/
+
+build/

packages/firebase_ml_custom/.metadata

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+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: b041144f833e05cf463b8887fa12efdec9493488
+  channel: stable
+
+project_type: plugin

packages/firebase_ml_custom/CHANGELOG.md

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+## 0.0.1
+
+* TODO: Describe initial release.

packages/firebase_ml_custom/LICENSE

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+// Copyright 2020 The Chromium Authors. All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//    * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//    * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//    * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

packages/firebase_ml_custom/README.md

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+# Firebase Machine Learning Custom
+
+[![pub package](https://img.shields.io/pub/v/firebase_ml_custom.svg)](https://pub.dartlang.org/packages/firebase_ml_custom)
+
+A Flutter plugin to use the [Firebase ML Custom Models API](https://firebase.google.com/docs/ml/use-custom-models).
+
+For Flutter plugins for other Firebase products, see [README.md](https://github.com/FirebaseExtended/flutterfire/blob/master/README.md).
+
+## Usage
+
+To use this plugin, add `firebase_ml_custom` as a [dependency in your pubspec.yaml file](https://flutter.io/platform-plugins/). You must also configure Firebase for each platform project: Android and iOS (see the example folder or https://codelabs.developers.google.com/codelabs/flutter-firebase/#4 for step by step details).
+
+### Android
+
+In order to use methods referencing those of [Firebase Model Manager](https://firebase.google.com/docs/reference/android/com/google/firebase/ml/common/modeldownload/FirebaseModelManager) minimum SDK version required is 24.
+Otherwise minimum SDK version is 21.
+This can be specified in your app-level `build.gradle` file.
+
+### iOS
+
+A minimum deployment target of 9.0 is required. You can add the line `platform :ios, '9.0'` in your iOS project `Podfile`.
+
+You may also need to update your app's deployment target to 9.0 using Xcode. Otherwise, you may see
+compilation errors.
+
+## Using Firebase Model Manager
+
+### 1. Create a `FirebaseCustomRemoteModel`.
+
+Create a `FirebaseCustomRemoteModel` object. 
+You should already have a model in your Firebase console available for download. Use the name that you gave your model in the Firebase console.
+
+```dart
+FirebaseCustomRemoteModel remoteModel = FirebaseCustomRemoteModel('myModelName');
+```
+
+### 2. Create a `FirebaseModelDownloadConditions`.
+
+Create a `FirebaseModelDownloadConditions` object.
+Specify optional platform-specific conditions for the model download.
+
+```dart
+FirebaseModelDownloadConditions conditions =
+    FirebaseModelDownloadConditions(
+        androidRequireWifi: true,
+        androidRequireDeviceIdle: true,
+        androidRequiredCharging: true,
+        iosAllowCellularAccess: false,
+        iosAllowBackgroundDownloading: true);
+```
+All of these parameters except `iosAllowCellularAccess` default to `false` if not specified. `iosAllowCellularAccess` defaults to `true`.
+Each platform looks only at its platform-specific parameters and ignores the rest.
+
+### 3. Create an instance of `FirebaseModelManager`.
+
+Create a `FirebaseModelManager` object corresponding to the default `FirebaseApp` instance.
+```dart
+FirebaseModelManager modelManager = FirebaseModelManager.instance;
+```
+
+### 4. Call `download()` with `FirebaseCustomRemoteModel` and `FirebaseModelDownloadConditions`.
+
+Initiate the download of a remote model if the download hasn't begun.
+If the model's download is already in progress, the current download task will continue executing.
+If the model is already downloaded to the device, and there is no update, the call will immediately succeed.
+If the model is already downloaded to the device, and there is update, a download for the updated version will be attempted.
+```dart
+await modelManager.download(remoteModel, conditions);
+```
+
+### 5. Call `isModelDownloaded()` with `FirebaseCustomRemoteModel`.
+
+Return whether the given remote model is currently downloaded.
+```dart
+if (await modelManager.isModelDownloaded(model) == true) ) {
+    // do something with this model
+} else {
+    // fall back on a locally-bundled model or do something else
+}
+```
+
+You can also check if download was successfully completed by surrounding download method with `try` and `catch`.
+
+### 5. Call `getLatestModelFile()` with `FirebaseCustomRemoteModel`.
+
+Return the `File` containing the latest model for the remote model name. This will fail if the model is not yet downloaded on the device or valid custom remote model is not provided.
+
+```dart
+File modelFile = await modelManager.getLatestModelFile(model);
+```
+
+You can feed this file directly into an interpreter or preprocess it, depending on the interpreter of your choice.
+
+Possible Flutter TF Lite interpreters:
+- [tflite](https://pub.dev/packages/tflite)
+- [tflite_flutter](https://pub.dev/packages/tflite_flutter)
+
+Google does not recommend usage of any specific interpreter and leaves it up to the user to decide.
+
+## Getting Started
+
+See the `example` directory for a complete sample app using Firebase Machine Learning Custom.
+
+## Issues and feedback
+
+Please file Flutterfire specific issues, bugs, or feature requests in our [issue tracker](https://github.com/FirebaseExtended/flutterfire/issues/new).
+
+Plugin issues that are not specific to Flutterfire can be filed in the [Flutter issue tracker](https://github.com/flutter/flutter/issues/new).
+
+To contribute a change to this plugin,
+please review our [contribution guide](https://github.com/FirebaseExtended/flutterfire/blob/master/CONTRIBUTING.md),
+and send a [pull request](https://github.com/FirebaseExtended/flutterfire/pulls).

packages/firebase_ml_custom/android/.gitignore

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+*.iml
+.gradle
+/local.properties
+/.idea/workspace.xml
+/.idea/libraries
+.DS_Store
+/build
+/captures

packages/firebase_ml_custom/android/build.gradle

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+group 'io.flutter.plugins.firebasemlcustom'
+version '1.0'
+
+buildscript {
+    repositories {
+        google()
+        jcenter()
+    }
+
+    dependencies {
+        classpath 'com.android.tools.build:gradle:3.5.0'
+    }
+}
+
+rootProject.allprojects {
+    repositories {
+        google()
+        jcenter()
+    }
+}
+
+apply plugin: 'com.android.library'
+
+android {
+    compileSdkVersion 28
+
+    defaultConfig {
+        minSdkVersion 16
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+    lintOptions {
+        disable 'InvalidPackage'
+    }
+    dependencies {
+        api 'com.google.firebase:firebase-ml-model-interpreter:22.0.3'
+        implementation 'androidx.annotation:annotation:1.0.0'
+        implementation 'androidx.exifinterface:exifinterface:1.0.0'
+    }
+}
+
+// TODO: Remove this hack once androidx.lifecycle is included on stable. https://github.com/flutter/flutter/issues/42348
+afterEvaluate {
+    def containsEmbeddingDependencies = false
+    for (def configuration : configurations.all) {
+        for (def dependency : configuration.dependencies) {
+            if (dependency.group == 'io.flutter' &&
+                    dependency.name.startsWith('flutter_embedding') &&
+                    dependency.isTransitive())
+            {
+                containsEmbeddingDependencies = true
+                break
+            }
+        }
+    }
+    if (!containsEmbeddingDependencies) {
+        android {
+            dependencies {
+                def lifecycle_version = "1.1.1"
+                implementation "android.arch.lifecycle:runtime:$lifecycle_version"
+                implementation "android.arch.lifecycle:common:$lifecycle_version"
+                implementation "android.arch.lifecycle:common-java8:$lifecycle_version"
+            }
+        }
+    }
+}
+
+apply from: file("./user-agent.gradle")

packages/firebase_ml_custom/android/gradle.properties

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+org.gradle.jvmargs=-Xmx1536M
+android.enableR8=true
+android.useAndroidX=true
+android.enableJetifier=true

packages/firebase_ml_custom/android/gradle/wrapper/gradle-wrapper.properties

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+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.2-all.zip

packages/firebase_ml_custom/android/settings.gradle

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+rootProject.name = 'firebase_ml_custom'