Eliminate the dependency of Profile from TtsMessageFilter.

chrome/browser/speech/tts_platform.h

Index: chrome/browser/speech/tts_platform.h
diff --git a/chrome/browser/speech/tts_platform.h b/chrome/browser/speech/tts_platform.h
index e396b7f78e748d0d55cf4868d726a9785ee3ebcf..c4a29e729651249b90a0512fc9ef11379973c0ea 100644
--- a/chrome/browser/speech/tts_platform.h
+++ b/chrome/browser/speech/tts_platform.h
@@ -23,7 +23,8 @@ class TtsPlatformImpl {
   // false if it's already loaded or if there's no extension to load.
   // Will call TtsController::RetrySpeakingQueuedUtterances when
   // the extension finishes loading.
-  virtual bool LoadBuiltInTtsExtension(Profile* profile);
+  virtual bool LoadBuiltInTtsExtension(
+      content::BrowserContext* browser_context);
 
   // Speak the given utterance with the given parameters if possible,
   // and return true on success. Utterance will always be nonempty.