Fix a typo in the external chrome.runtime docs

Test: None
Bug: None
Change-Id: I47c1f70860ed364fdfecb403a29c3d8a1ab8b4ce
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2067757Reviewed-by: David Munro <davidmunro@google.com>
Reviewed-by: Istiaque Ahmed <lazyboy@chromium.org>
Reviewed-by: Ben Wells <benwells@chromium.org>
Commit-Queue: David Munro <davidmunro@google.com>
Auto-Submit: David Munro <davidmunro@google.com>
Cr-Commit-Position: refs/heads/master@{#743426}

extensions/common/api/runtime.json

@@ -61,7 +61,7 @@
           "url": {"type": "string", "optional": true, "description": "The URL of the page or frame that opened the connection. If the sender is in an iframe, it will be iframe's URL not the URL of the page which hosts it."},
           "nativeApplication": {"type": "string", "optional": true, "description": "The name of the native application that opened the connection, if any."},
           "tlsChannelId": {"type": "string", "optional": true, "description": "The TLS channel ID of the page or frame that opened the connection, if requested by the extension or app, and if available."},
-	  "origin": {"type": "string", "optional": true, "description": "The origin of the page or frame that opened the connection. It can vary from the url property (e.g., about:blank) or can be opaque (e.g., sandboxed iframes). This is useful for identifying if the origin can be trust if we can't immediately tell from the URL."}
+        "origin": {"type": "string", "optional": true, "description": "The origin of the page or frame that opened the connection. It can vary from the url property (e.g., about:blank) or can be opaque (e.g., sandboxed iframes). This is useful for identifying if the origin can be trusted if we can't immediately tell from the URL."}
     }
       },
       {