4 files changed, 37 insertions, 1 deletions
diff --git a/chrome/common/extensions/extension.cc b/chrome/common/extensions/extension.cc
index f898a52..1ea3041d 100644
--- a/chrome/common/extensions/extension.cc
+++ b/chrome/common/extensions/extension.cc
@@ -63,6 +63,9 @@ const char kPrivate[] = "PRIVATE";
 
 const int kRSAKeySize = 1024;
 
+const char kDefaultContentSecurityPolicy[] =
+    "script-src 'self'; object-src 'self'";
+
 // Converts a normal hexadecimal string into the alphabet used by extensions.
 // We use the characters 'a'-'p' instead of '0'-'f' to avoid ever having a
 // completely numeric host, since some software interprets that as an IP
@@ -1275,7 +1278,8 @@ bool Extension::IsTrustedId(const std::string& id) {
 }
 
 Extension::Extension(const FilePath& path, Location location)
-    : incognito_split_mode_(false),
+    : manifest_version_(0),
+      incognito_split_mode_(false),
       offline_enabled_(false),
       location_(location),
       converted_from_user_script_(false),
@@ -1454,6 +1458,19 @@ bool Extension::InitFromValue(const DictionaryValue& source, int flags,
   optional_permission_set_ = new ExtensionPermissionSet();
   required_permission_set_ = new ExtensionPermissionSet();
 
+  if (source.HasKey(keys::kManifestVersion)) {
+    int manifest_version = 0;
+    if (!source.GetInteger(keys::kManifestVersion, &manifest_version) ||
+        manifest_version < 1) {
+      *error = errors::kInvalidManifestVersion;
+      return false;
+    }
+    manifest_version_ = manifest_version;
+  } else {
+    // Version 1 was the original version, which lacked a version indicator.
+    manifest_version_ = 1;
+  }
+
   if (source.HasKey(keys::kPublicKey)) {
     std::string public_key_bytes;
     if (!source.GetString(keys::kPublicKey,
@@ -2217,6 +2234,11 @@ bool Extension::InitFromValue(const DictionaryValue& source, int flags,
       return false;
     }
     content_security_policy_ = content_security_policy;
+  } else if (manifest_version_ >= 2) {
+    // Manifest version 2 introduced a default Content-Security-Policy.
+    // TODO(abarth): Should we continue to let extensions override the
+    //               default Content-Security-Policy?
+    content_security_policy_ = kDefaultContentSecurityPolicy;
   }
 
   // Initialize devtools page url (optional).
diff --git a/chrome/common/extensions/extension.h b/chrome/common/extensions/extension.h
index 9aefb4c..146c534 100644
--- a/chrome/common/extensions/extension.h
+++ b/chrome/common/extensions/extension.h
@@ -494,6 +494,7 @@ class Extension : public base::RefCountedThreadSafe<Extension> {
   const std::string& name() const { return name_; }
   const std::string& public_key() const { return public_key_; }
   const std::string& description() const { return description_; }
+  int manifest_version() const { return manifest_version_; }
   bool converted_from_user_script() const {
     return converted_from_user_script_;
   }
@@ -714,6 +715,14 @@ class Extension : public base::RefCountedThreadSafe<Extension> {
   // The absolute path to the directory the extension is stored in.
   FilePath path_;
 
+  // The version of this extension's manifest. We increase the manifest
+  // version when making breaking changes to the extension system.
+  // Version 1 was the first manifest version (implied by a lack of a
+  // manifest_version attribute in the extension's manifest). We initialize
+  // this member variable to 0 to distinguish the "uninitialized" case from
+  // the case when we know the manifest version actually is 1.
+  int manifest_version_;
+
   // Default locale for fall back. Can be empty if extension is not localized.
   std::string default_locale_;
 
diff --git a/chrome/common/extensions/extension_constants.cc b/chrome/common/extensions/extension_constants.cc
index b0bb370..85bfd52 100644
--- a/chrome/common/extensions/extension_constants.cc
+++ b/chrome/common/extensions/extension_constants.cc
@@ -53,6 +53,7 @@ const char* kLaunchLocalPath = "app.launch.local_path";
 const char* kLaunchWebURL = "app.launch.web_url";
 const char* kLaunchWidth = "app.launch.width";
 const char* kLayouts = "layouts";
+const char* kManifestVersion = "manifest_version";
 const char* kMatches = "matches";
 const char* kMinimumChromeVersion = "minimum_chrome_version";
 const char* kName = "name";
@@ -271,6 +272,8 @@ const char* kInvalidLaunchWidthContainer =
     "Invalid container type for 'app.launch.width'.";
 const char* kInvalidManifest =
     "Manifest file is invalid.";
+const char* kInvalidManifestVersion =
+    "Invalid value for 'manifest_version'.";
 const char* kInvalidMatch =
     "Invalid value for 'content_scripts[*].matches[*]': *";
 const char* kInvalidMatchCount =
diff --git a/chrome/common/extensions/extension_constants.h b/chrome/common/extensions/extension_constants.h
index 1f47f8f..ecdb13d 100644
--- a/chrome/common/extensions/extension_constants.h
+++ b/chrome/common/extensions/extension_constants.h
@@ -55,6 +55,7 @@ namespace extension_manifest_keys {
   extern const char* kLaunchWebURL;
   extern const char* kLaunchWidth;
   extern const char* kLayouts;
+  extern const char* kManifestVersion;
   extern const char* kMatches;
   extern const char* kMinimumChromeVersion;
   extern const char* kNaClModules;
@@ -203,6 +204,7 @@ namespace extension_manifest_errors {
   extern const char* kInvalidLaunchWidth;
   extern const char* kInvalidLaunchWidthContainer;
   extern const char* kInvalidManifest;
+  extern const char* kInvalidManifestVersion;
   extern const char* kInvalidMatch;
   extern const char* kInvalidMatchCount;
   extern const char* kInvalidMatches;