Convert utility process ParseMediaMetadata blob reading IPC to mojo

chrome/common/extensions/media_parser.mojom

Index: chrome/common/extensions/media_parser.mojom
diff --git a/chrome/common/extensions/media_parser.mojom b/chrome/common/extensions/media_parser.mojom
index cc700c5acc0b171df1515bc1316ba8bb39c67785..8f296564849ce2faddb9a4f0207fb57d406a60b4 100644
--- a/chrome/common/extensions/media_parser.mojom
+++ b/chrome/common/extensions/media_parser.mojom
@@ -11,15 +11,15 @@ import "mojo/common/file.mojom";
 import "mojo/common/time.mojom";
 import "mojo/common/values.mojom";
 
-struct AttachedImage {
-  string type;
-  array<uint8> data;
-};
-
 interface MediaParser {
+  // Extract metadata from a |mime_type| blob of data of |total_size| and
+  // available from the browser process via |media_data_source|. If there
+  // are images referred to in the metadata, and |get_attached_images| is
+  // true, return the images in |attached_images|.
   ParseMediaMetadata(string mime_type,
                      int64 total_size,
-                     bool get_attached_images)
+                     bool get_attached_images,
+                     MediaDataSource media_data_source)
       => (bool parse_success,
           mojo.common.mojom.DictionaryValue metadata,
           array<AttachedImage> attached_images);
@@ -33,3 +33,16 @@ interface MediaParser {
                  mojo.common.mojom.File file)
       => (bool success);
 };
+
+interface MediaDataSource {
+  // ParseMediaMetadata interface used to read blob data for parsing from
+  // the browser process.
+  ReadBlob(int64 position, int64 length) => (array<uint8> data);
+};
+
+struct AttachedImage {
+  // If ParseMediaMetadata returns attached images, each of the images is
+  // returned in an AttachedImage object.
+  string type;
+  array<uint8> data;
+};