Renamed browser-side to main process

renamed a few occurances of "web page" to "renderer"
renamed a few files that had "browser" in their name to "main-process"
note that there are still many occurances of web page.

docs/api/ipc-main-process.md

@@ -0,0 +1,49 @@
+# ipc (main process)
+
+Handles asynchronous and synchronous message sent from a renderer process (web
+page).
+
+The messages sent from a renderer would be emitted to this module, the event name
+is the `channel` when sending message. To reply a synchronous message, you need
+to set `event.returnValue`, to send an asynchronous back to the sender, you can
+use `event.sender.send(...)`.
+
+It's also possible to send messages from main process to the renderer process,
+see [WebContents.send](browser-window.md#webcontentssendchannel-args) for more.
+
+An example of sending and handling messages:
+
+```javascript
+// In main process.
+var ipc = require('ipc');
+ipc.on('asynchronous-message', function(event, arg) {
+  console.log(arg);  // prints "ping"
+  event.sender.send('asynchronous-reply', 'pong');
+});
+
+ipc.on('synchronous-message', function(event, arg) {
+  console.log(arg);  // prints "ping"
+  event.returnValue = 'pong';
+});
+```
+
+```javascript
+// In renderer process (web page).
+var ipc = require('ipc');
+console.log(ipc.sendSync('synchronous-message', 'ping')); // prints "pong"
+
+ipc.on('asynchronous-reply', function(arg) {
+  console.log(arg); // prints "pong"
+});
+ipc.send('asynchronous-message', 'ping');
+```
+
+## Class: Event
+
+### Event.returnValue
+
+Assign to this to return an value to synchronous messages.
+
+### Event.sender
+
+The `WebContents` of the renderer that has sent the message.