Files.app: Add private API to check if PiexLoader is enabled or not.

PiexLoader is enabled only for official build.

BUG=396702
TEST=None
R=isherman@chromium.org

Review URL: https://codereview.chromium.org/1026733003

Cr-Commit-Position: refs/heads/master@{#321933}

chrome/browser/chromeos/extensions/file_manager/private_api_misc.cc

@@ -460,4 +460,15 @@ void FileManagerPrivateGetMimeTypeFunction::OnGetMimeType(
   SendResponse(true);
 }
 
+ExtensionFunction::ResponseAction
+FileManagerPrivateIsPiexLoaderEnabledFunction::Run() {
+#if defined(OFFICIAL_BUILD)
+  return RespondNow(OneArgument(
+      new base::FundamentalValue(true)));
+#else
+  return RespondNow(OneArgument(
+      new base::FundamentalValue(false)));
+#endif
+}
+
 }  // namespace extensions

chrome/browser/chromeos/extensions/file_manager/private_api_misc.h

@@ -181,6 +181,21 @@ class FileManagerPrivateGetMimeTypeFunction
   void OnGetMimeType(const std::string& mimeType);
 };
 
+// Implements the chrome.fileManagerPrivate.isPiexLoaderEnabled method.
+class FileManagerPrivateIsPiexLoaderEnabledFunction
+    : public UIThreadExtensionFunction {
+ public:
+  FileManagerPrivateIsPiexLoaderEnabledFunction() {}
+  DECLARE_EXTENSION_FUNCTION("fileManagerPrivate.isPiexLoaderEnabled",
+                             FILEMANAGERPRIVATE_ISPIEXLOADERENABLED)
+ protected:
+  ~FileManagerPrivateIsPiexLoaderEnabledFunction() override {}
+
+ private:
+  ResponseAction Run() override;
+  DISALLOW_COPY_AND_ASSIGN(FileManagerPrivateIsPiexLoaderEnabledFunction);
+};
+
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_CHROMEOS_EXTENSIONS_FILE_MANAGER_PRIVATE_API_MISC_H_

chrome/common/extensions/api/file_manager_private.idl

@@ -872,6 +872,9 @@ interface Functions {
                           DOMString key,
                           DOMString value,
                           SimpleCallback callback);
+
+  // Returns if Piex loader is enabled.
+  static void isPiexLoaderEnabled(BooleanCallback callback);
 };
 
 interface Events {

extensions/browser/extension_function_histogram_value.h

@@ -1041,6 +1041,7 @@ enum HistogramValue {
   FILEMANAGERPRIVATE_ENABLEEXTERNALFILESCHEME,
   DEVELOPERPRIVATE_UPDATEEXTENSIONCONFIGURATION,
   DEVELOPERPRIVATE_DELETEEXTENSIONERRORS,
+  FILEMANAGERPRIVATE_ISPIEXLOADERENABLED,
   // Last entry: Add new entries above and ensure to update
   // tools/metrics/histograms/histograms.xml.
   ENUM_BOUNDARY

third_party/closure_compiler/externs/file_manager_private.js

@@ -574,6 +574,12 @@ chrome.fileManagerPrivate.isUMAEnabled = function(callback) {};
  */
 chrome.fileManagerPrivate.setEntryTag = function(entryURL, visibility, key, value, callback) {};
 
+/**
+ * Gets a flag indicating whether PiexLoader is enabled.
+ * @param {function(boolean)} callback
+ */
+chrome.fileManagerPrivate.isPiexLoaderEnabled = function(callback) {};
+
 /** @type {!ChromeEvent} */
 chrome.fileManagerPrivate.onMountCompleted;
 

tools/metrics/histograms/histograms.xml

@@ -49317,6 +49317,7 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="980" label="FILEMANAGERPRIVATE_ENABLEEXTERNALFILESCHEME"/>
   <int value="981" label="DEVELOPERPRIVATE_UPDATEEXTENSIONCONFIGURATION"/>
   <int value="982" label="DEVELOPERPRIVATE_DELETEEXTENSIONERRORS"/>
+  <int value="983" label="FILEMANAGERPRIVATE_ISPIEXLOADERENABLED"/>
 </enum>
 
 <enum name="ExtensionInstallCause" type="int">