[Android][Resolved] Error:Execution failed for task ':app:processDebugGoogleServices'. > No matching client found for package name 'testing.fcm'

Error message:

Error:Execution failed for task ':app:processDebugGoogleServices'. > No matching client found for package name 'testing.fcm'

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="fcm.testing.firetest">
    <uses-permission android:name="android.permission.INTERNET" />
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>

build.gradlein Module :app

apply plugin: 'com.android.application'
android {
    compileSdkVersion 23
    buildToolsVersion "23.0.2"
    defaultConfig {
        applicationId "testing.fcm"//fcm.testing.firetest
        minSdkVersion 11
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.4.0'
    compile 'com.google.firebase:firebase-messaging:9.0.0'
    compile 'com.squareup.okhttp3:okhttp:3.2.0'
}
apply plugin: 'com.google.gms.google-services'

Solution : 

Correct the applicationId in defaultConfig and make the value same as build.gradle in Module :app

apply plugin: 'com.android.application'
android {
    compileSdkVersion 23
    buildToolsVersion "23.0.2"
    defaultConfig {
        applicationId "fcm.testing.firetest"
        minSdkVersion 11
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.4.0'
    compile 'com.google.firebase:firebase-messaging:9.0.0'
    compile 'com.squareup.okhttp3:okhttp:3.2.0'
}
apply plugin: 'com.google.gms.google-services'

And then compile again.

Reference:
http://stackoverflow.com/questions/34679411/android-studio-gradle-errorexecution-failed-for-task-appprocessdebuggoogles , by Hiren