Electronic privacy is current ruled by the "Third Party Doctrine" from the case Smith, Miller, and Katz. I think SCOTUS just largely replaced that with the "Rummaging Doctrine" in Riley v California.
The Third Party Doctrine was the principle that once you give up your data to a third party, that data is no longer covered by the Fourth Amendment. That's because you no longer have a "reasonable expectation of privacy". Thus, you have no reasonable expectation of privacy in your phone call records, so the police can grab them without a warrant.
Riley changes the direction of that arrow. It's no longer about your privacy, it's about the government's power -- the power that comes from unrestrained rummaging through a person's effects. It's not longer about whether I want something private, it's about whether the police properly wants something revealed. The properness is defined as the idea that police must already have good reason to suspect somebody of a crime, and must only be looking for evidence of that specific crime. They can't go on fishing expeditions.
SCOTUS goes so far as to declare the revolution, that it's right and proper to take up arms against governments who rummage through our effects. They cite the case of John Adams taking up arms against the 'writs of assistance', which were search warrants that never expired allowing British agents to search indiscriminately. The modern version of such writs is the Verizon court order renewed every three months for the last 8 years demanding all phone metadata. I think the court is signalling a complete exoneration of Edward Snowden leaking that writ to the public.
Right now, the government can go to Yahoo and request the last 15 years of my email stored on their servers, without a warrant, just in case I might've commit a crime. Right now, the government grabs all my phone and financial records, even though they don't suspect me of a crime, and then apply computer algorithms puting that data together in order to see if evidence of crime falls out. To travel on planes, I first have to prove to the government that I'm innocent. That's rummaging in full 'writs of assistance' style, and I'm pretty sure SCOTUS just said they are going to strike that stuff down.