ClickOnwebElement not working

[Rubhal]

Hi,
I am trying to click on a button inside web view.
My test code is:
public void testButtonClick() throws Exception{
WebView webView = (WebView) solo.getView(R.id.webView1);
solo.waitForView(webView, 2000, false);
By installButton=By.xpath("//button[@Class="price buy id-track-click id-track-impression"]");
solo.waitForWebElement(installButton, 60000, false);
solo.clickOnWebElement(installButton, 0, false);
}

I am loading the webpage with url:
https://play.google.com/store/apps/details?id=com.whatsapp&hl=en

I have to click on the install button automatically. When i run this code i am getting webelement with xpath not found. please help me with this issue.

Thanks in advance!!