Implement mimetype sniffing for extensions.

chrome/common/extensions/extension.cc

Index: chrome/common/extensions/extension.cc
diff --git a/chrome/common/extensions/extension.cc b/chrome/common/extensions/extension.cc
index fc13d3aec2a538966728c92c9124f23405b20f9b..8097d5e50b6352a2e24ffcc040038e1404be444f 100644
--- a/chrome/common/extensions/extension.cc
+++ b/chrome/common/extensions/extension.cc
@@ -74,6 +74,8 @@ const char* Extension::kExtensionRegistryPath =
 // first 16 bytes of SHA256 hashed public key.
 const size_t Extension::kIdSize = 16;
 
+const char Extension::kMimeType[] = "application/x-chrome-extension";
+
 const int Extension::kKnownIconSizes[] = { 128 };
 
 Extension::~Extension() {
@@ -87,12 +89,12 @@ const std::string Extension::VersionString() const {
 }
 
 // static
-bool Extension::IsExtension(const FilePath& file_name) {
-  return file_name.MatchesExtension(
-      FilePath::StringType(FILE_PATH_LITERAL(".")) +
-      chrome::kExtensionFileExtension);
-}
-
+bool Extension::IsExtension(const FilePath& file_name) {
+  return file_name.MatchesExtension(
+      FilePath::StringType(FILE_PATH_LITERAL(".")) +
+      chrome::kExtensionFileExtension);
+}
+
 // static
 bool Extension::IdIsValid(const std::string& id) {
   // Verify that the id is legal.