Convert Spellcheck host MessageFilter IPC to mojo

components/spellcheck/common/spellcheck.mojom

Index: components/spellcheck/common/spellcheck.mojom
diff --git a/components/spellcheck/common/spellcheck.mojom b/components/spellcheck/common/spellcheck.mojom
index 91952616731a552d95c63ebbb6cfa93a6889e1e3..f9169ae62e160be9bb7b3563f74280cfe41ab397 100644
--- a/components/spellcheck/common/spellcheck.mojom
+++ b/components/spellcheck/common/spellcheck.mojom
@@ -5,6 +5,7 @@
 module spellcheck.mojom;
 
 import "mojo/common/file.mojom";
+import "mojo/common/string16.mojom";
 
 // Render process interface exposed to the browser for receiving process-
 // wide spellcheck control and updates from the browser process.
@@ -26,3 +27,27 @@ struct SpellCheckBDictLanguage {
   mojo.common.mojom.File? file;
   string language;
 };
+
+// Browser process interface exposed to the renderer for requesting spell-
+// check host services.
+//
+interface SpellCheckHost {
+  // Asks the browser to initialize the renderer's spellchecker: the spell
+  // checker initialize call arrives on spellcheck::mojom::SpellChecker in
+  // async response to this request.
+  RequestDictionary();
+
+  // Tracks spell checking occurrences to collect histograms, where |word|
+  // was checked, and |misspelled| is true if |word| was misspelt.
+  NotifyChecked(mojo.common.mojom.String16 word, bool misspelled);
+
+  // Asks the host to spellcheck the |text| using a remote Spelling server
+  // to do the spellchecking. If the remote Spelling server is available,
+  // returns |success| true, and the spellchecked |results|. Note this API
+  // requires a !BUILDFLAG(USE_BROWSER_SPELLCHECKER) build.
+  CallSpellingService(mojo.common.mojom.String16 text) =>
+      (bool success, array<SpellCheckResult> results);
+};
+
+[Native]
+struct SpellCheckResult;