Fix for bug 8577776 Throw exception if app calls WebView used on wrong thread

import android.graphics.Rect;

import android.graphics.drawable.Drawable;

import android.net.http.SslCertificate;

import android.os.Build;

import android.os.Bundle;

import android.os.Looper;

import android.os.Message;

    private static final String LOGTAG = "webview_proxy";

    // Throwing an exception for incorrect thread usage if the

    // build target is JB MR2 or newer. Defaults to false, and is

    // set in the WebView constructor.

    private static Boolean sEnforceThreadChecking = false;

    /**

     *  Transportation object for returning WebView across thread boundaries.

     */

        if (context == null) {

            throw new IllegalArgumentException("Invalid context argument");

        }

        sEnforceThreadChecking = context.getApplicationInfo().targetSdkVersion >=

                Build.VERSION_CODES.JELLY_BEAN_MR2;

        checkThread();

        ensureProviderCreated();

                    "Future versions of WebView may not support use on other threads.");

            Log.w(LOGTAG, Log.getStackTraceString(throwable));

            StrictMode.onWebViewMethodCalledOnWrongThread(throwable);

            if (sEnforceThreadChecking) {

                throw new RuntimeException(throwable);

            }

        }

    }