Docserver: Implement the content providers infrastructure, where a

chrome/common/extensions/docs/templates/json/content_providers.json

Index: chrome/common/extensions/docs/templates/json/content_providers.json
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+// === Overview ===
+//
+// This file configures where to find and how to serve content in the docserver.
+// It's the most fundamentally important file in all of the docserver.
+//
+// === Format ===
+//
+// Each entry declares a rule with:
+//  * An arbitrary identifier key e.g. "cr-extensions-examples".
+//  * What URL the rule should be invoked with, given by "serveFrom", e.g.
+//    "extensions/examples".
+//  * An object describing where the content originates; currently the only
+//    supported location is "chromium" with a key "dir" specifying which
+//    chromium directory to look in, e.g. "extensions/samples".
+//
+// In this example, when the user navigates to
+//
+//    developer.chrome.com/extensions/examples/some/sample/path
+//
+// then
+//  1. The "cr-extensions-examples" rule is invoked (since it's served from
+//     "extensions/examples").
+//  2. The docserver will look up the path "docs/examples/some/sample/path"
+//     in chromium - the URL after the "serveFrom" path (some/sample/path)
+//     prefixed by the chromium directory (docs/examples).
+//  3. Then render and serve it.
+//
+// === Special properties ===
+//
+// There are some other properties that can be specified:
+//  * "supportsZip" indicates whether directories are allowed to be served as
+//    zip files. For safety this isn't supported for arbitrary URLs, only those
+//    within a rule that has "supportsZip": true.
+//  * "supportsTemplates" indicates whether HTML files should be treated and
+//    renderered as templates, versus just plain text. Complex documentation
+//    which interacts with docserver features (like API listing) need to set
+//    this to true. Otherwise, it's safer and more efficient to omit it.
+
+{
+  "cr-extensions-examples": {
+    "chromium": {
+      "dir": "docs/examples"
+    },
+    "serveFrom": "extensions/examples",
+    "supportsZip": true
+  },
+  "cr-public": {
+    "chromium": {
+      "dir": "docs/templates/public"
+    },
+    "serveFrom": "",
+    "supportsTemplates": true
+  },
+  "cr-static": {
+    "chromium": {
+      "dir": "docs/static"
+    },
+    "serveFrom": "static"
+  }
+}