Avoid "duplicate FILE_MANAGER_HOST" warnings

Also fix a "missing semicolon" JS presubmit failure.

Cq-Include-Trybots: luci.chromium.try:closure_compilation
Change-Id: Ib607e0e25c74ff85cc9d5ba2f23c596e0f509723
Reviewed-on: https://chromium-review.googlesource.com/1100660
Commit-Queue: Nigel Tao <nigeltao@chromium.org>
Reviewed-by: Sasha Morrissey <sashab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568667}

ui/file_manager/file_manager/foreground/js/metadata/exif_parser.js

@@ -4,13 +4,21 @@
 
 /**
  * Protocol + host parts of extension URL.
+ *
+ * The __FILE_NAME suffix is because the same string constant is used in
+ * multiple JS files, and JavaScript doesn't have C's #define mechanism (which
+ * only affects the file its in). Without the suffix, we'd have "constant
+ * FILE_MANAGER_HOST assigned a value more than once" compiler warnings.
+ *
  * @type {string}
  * @const
  */
-var FILE_MANAGER_HOST = 'chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj';
+var FILE_MANAGER_HOST__EXIF_PARSER =
+    'chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj';
 
 importScripts(
-    FILE_MANAGER_HOST + '/foreground/js/metadata/exif_constants.js');
+    FILE_MANAGER_HOST__EXIF_PARSER +
+    '/foreground/js/metadata/exif_constants.js');
 
 function ExifParser(parent) {
   ImageParser.call(this, parent, 'jpeg', /\.jpe?g$/i);
@@ -311,8 +319,9 @@ ExifParser.prototype.readTagValue = function(br, tag) {
    * @param {boolean=} opt_signed
    */
   function unsafeRead(size, opt_readFunction, opt_signed) {
-    var readFunction = opt_readFunction ||
-        function(size) { return br.readScalar(size, opt_signed) };
+    var readFunction = opt_readFunction || function(size) {
+      return br.readScalar(size, opt_signed);
+    };
 
     var totalSize = tag.componentCount * size;
     if (totalSize < 1) {

ui/file_manager/file_manager/foreground/js/metadata/id3_parser.js

@@ -4,15 +4,24 @@
 
 /**
  * Protocol + host parts of extension URL.
+ *
+ * The __FILE_NAME suffix is because the same string constant is used in
+ * multiple JS files, and JavaScript doesn't have C's #define mechanism (which
+ * only affects the file its in). Without the suffix, we'd have "constant
+ * FILE_MANAGER_HOST assigned a value more than once" compiler warnings.
+ *
  * @type {string}
  * @const
  */
-var FILE_MANAGER_HOST = 'chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj';
+var FILE_MANAGER_HOST__ID3_PARSER =
+    'chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj';
 
 importScripts(
-    FILE_MANAGER_HOST + '/foreground/js/metadata/function_sequence.js');
+    FILE_MANAGER_HOST__ID3_PARSER +
+    '/foreground/js/metadata/function_sequence.js');
 importScripts(
-    FILE_MANAGER_HOST + '/foreground/js/metadata/function_parallel.js');
+    FILE_MANAGER_HOST__ID3_PARSER +
+    '/foreground/js/metadata/function_parallel.js');
 
 /**
  * ID3 parser.

ui/file_manager/file_manager/foreground/js/metadata/metadata_dispatcher.js

@@ -4,16 +4,27 @@
 
 /**
  * Protocol + host parts of extension URL.
+ *
+ * The __FILE_NAME suffix is because the same string constant is used in
+ * multiple JS files, and JavaScript doesn't have C's #define mechanism (which
+ * only affects the file its in). Without the suffix, we'd have "constant
+ * FILE_MANAGER_HOST assigned a value more than once" compiler warnings.
+ *
  * @type {string}
  * @const
  */
-var FILE_MANAGER_HOST = 'chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj';
+var FILE_MANAGER_HOST__METADATA_DISPATCHER =
+    'chrome-extension://hhaomjibdihmijegdhdafkllkbggdgoj';
 
 // All of these scripts could be imported with a single call to importScripts,
 // but then load and compile time errors would all be reported from the same
 // line.
-importScripts(FILE_MANAGER_HOST + '/foreground/js/metadata/metadata_parser.js');
-importScripts(FILE_MANAGER_HOST + '/foreground/js/metadata/byte_reader.js');
+importScripts(
+    FILE_MANAGER_HOST__METADATA_DISPATCHER +
+    '/foreground/js/metadata/metadata_parser.js');
+importScripts(
+    FILE_MANAGER_HOST__METADATA_DISPATCHER +
+    '/foreground/js/metadata/byte_reader.js');
 
 /**
  * Dispatches metadata requests to the correct parser.
@@ -29,10 +40,18 @@ function MetadataDispatcher(port) {
 
   // Make sure to update component_extension_resources.grd
   // when adding new parsers.
-  importScripts(FILE_MANAGER_HOST + '/foreground/js/metadata/exif_parser.js');
-  importScripts(FILE_MANAGER_HOST + '/foreground/js/metadata/image_parsers.js');
-  importScripts(FILE_MANAGER_HOST + '/foreground/js/metadata/mpeg_parser.js');
-  importScripts(FILE_MANAGER_HOST + '/foreground/js/metadata/id3_parser.js');
+  importScripts(
+      FILE_MANAGER_HOST__METADATA_DISPATCHER +
+      '/foreground/js/metadata/exif_parser.js');
+  importScripts(
+      FILE_MANAGER_HOST__METADATA_DISPATCHER +
+      '/foreground/js/metadata/image_parsers.js');
+  importScripts(
+      FILE_MANAGER_HOST__METADATA_DISPATCHER +
+      '/foreground/js/metadata/mpeg_parser.js');
+  importScripts(
+      FILE_MANAGER_HOST__METADATA_DISPATCHER +
+      '/foreground/js/metadata/id3_parser.js');
 
   var patterns = [];