Google Drive Quick Start with Android Studio

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.smokybob.testgdrive"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="19" />
    <uses-permission
        android:name="android.permission.INTERNET" />
    
    <uses-permission
        android:name="android.permission.GET_ACCOUNTS" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.smokybob.testgdrive.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <meta-data android:name="com.google.android.gms.version"
            android:value="@integer/google_play_services_version" />
    </application>

</manifest>

build.gradle

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.6.+'
    }
}
apply plugin: 'android'

repositories {
    mavenCentral()
}

android {
    compileSdkVersion 19
    buildToolsVersion "17.0.0"

    defaultConfig {
        minSdkVersion 8
        targetSdkVersion 19
    }
    buildTypes {
        release {
            runProguard true
            proguardFile getDefaultProguardFile('proguard-android-optimize.txt')
        }
    }
    productFlavors {
        defaultFlavor {
            proguardFile 'proguard-rules.txt'
        }
    }
}

dependencies {
	compile 'com.android.support:appcompat-v7:+'
    compile 'com.google.android.gms:play-services:4.0.30'

    compile 'com.android.support:support-v4:19.0.0'
    compile('com.google.api-client:google-api-client-xml:1.17.0-rc') {
        exclude group: 'com.google.android.google-play-services'
    }
    compile 'com.google.http-client:google-http-client-gson:1.17.0-rc'
    compile('com.google.api-client:google-api-client-android:1.17.0-rc') {
        exclude group: 'com.google.android.google-play-services'
    }
    compile 'com.google.apis:google-api-services-drive:v2-rev105-1.17.0-rc'
}

MainActivity.java

package com.smokybob.testgdrive;

import android.accounts.AccountManager;
import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
import android.widget.Toast;

import com.google.api.client.extensions.android.http.AndroidHttp;
import com.google.api.client.googleapis.extensions.android.gms.auth.GoogleAccountCredential;
import com.google.api.client.googleapis.extensions.android.gms.auth.UserRecoverableAuthIOException;
import com.google.api.client.http.FileContent;
import com.google.api.client.json.gson.GsonFactory;
import com.google.api.services.drive.Drive;
import com.google.api.services.drive.DriveScopes;
import com.google.api.services.drive.model.File;

import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Date;
import java.util.Locale;

public class MainActivity extends ActionBarActivity {

    static final int REQUEST_ACCOUNT_PICKER = 1;
    static final int REQUEST_AUTHORIZATION = 2;
    static final int CAPTURE_IMAGE = 3;

    private static Uri fileUri;
    private static Drive service;
    private GoogleAccountCredential credential;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment())
                    .commit();
        }

        credential = GoogleAccountCredential.usingOAuth2(this, Arrays.asList(DriveScopes.DRIVE));
        startActivityForResult(credential.newChooseAccountIntent(), REQUEST_ACCOUNT_PICKER);

    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {

        public PlaceholderFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container, false);
            return rootView;
        }
    }

    @Override
    protected void onActivityResult(final int requestCode, final int resultCode, final Intent data) {
        switch (requestCode) {
            case REQUEST_ACCOUNT_PICKER:
                if (resultCode == RESULT_OK && data != null && data.getExtras() != null) {
                    String accountName = data.getStringExtra(AccountManager.KEY_ACCOUNT_NAME);
                    if (accountName != null) {
                        credential.setSelectedAccountName(accountName);
                        service = getDriveService(credential);
                        startCameraIntent();
                    }
                }
                break;
            case REQUEST_AUTHORIZATION:
                if (resultCode == Activity.RESULT_OK) {
                    saveFileToDrive();
                } else {
                    startActivityForResult(credential.newChooseAccountIntent(), REQUEST_ACCOUNT_PICKER);
                }
                break;
            case CAPTURE_IMAGE:
                if (resultCode == Activity.RESULT_OK) {
                    saveFileToDrive();
                }
        }
    }

    private void startCameraIntent() {
        String mediaStorageDir = Environment.getExternalStoragePublicDirectory(
                Environment.DIRECTORY_PICTURES).getPath();
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss", Locale.US).format(new Date());
        fileUri = Uri.fromFile(new java.io.File(mediaStorageDir + java.io.File.separator + "IMG_"
                + timeStamp + ".jpg"));

        Intent cameraIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        cameraIntent.putExtra(MediaStore.EXTRA_OUTPUT, fileUri);
        startActivityForResult(cameraIntent, CAPTURE_IMAGE);
    }

    private void saveFileToDrive() {
        Thread t = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    // File's binary content
                    java.io.File fileContent = new java.io.File(fileUri.getPath());
                    FileContent mediaContent = new FileContent("image/jpeg", fileContent);

                    // File's metadata.
                    File body = new File();
                    body.setTitle(fileContent.getName());
                    body.setMimeType("image/jpeg");

                    File file = service.files().insert(body, mediaContent).execute();
                    if (file != null) {
                        showToast("Photo uploaded: " + file.getTitle());
                        startCameraIntent();
                    }
                } catch (UserRecoverableAuthIOException e) {
                    startActivityForResult(e.getIntent(), REQUEST_AUTHORIZATION);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });
        t.start();
    }

    private Drive getDriveService(GoogleAccountCredential credential) {
        return new Drive.Builder(AndroidHttp.newCompatibleTransport(), new GsonFactory(), credential)
                .build();
    }

    public void showToast(final String toast) {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                Toast.makeText(getApplicationContext(), toast, Toast.LENGTH_SHORT).show();
            }
        });
    }
}

Thank you kind Sir!

Gradle script needs update though!
runProguard has been renamed minifyEnabled & versions