Expose way to set google api key through CWVWebView class method.

ios/web_view/public/cwv_web_view.h

Index: ios/web_view/public/cwv_web_view.h
diff --git a/ios/web_view/public/cwv_web_view.h b/ios/web_view/public/cwv_web_view.h
index 86de8f52c87bbe10faf941d4d1f072f25e2db55a..d2d5a9c94a7768e86a5dbc4d93ffc31fce867cf7 100644
--- a/ios/web_view/public/cwv_web_view.h
+++ b/ios/web_view/public/cwv_web_view.h
@@ -61,6 +61,15 @@ CWV_EXPORT
 // is reset to 0.0.
 @property(nonatomic, readonly) double estimatedProgress;
 
+// Use this method to set the necessary credentials used to communicate with
+// the Google API for features such as translate. See this link for more info:
+// https://support.google.com/googleapi/answer/6158857
+// This method must be called before any |CWVWebViews| are instantiated for
+// the keys to be used.
++ (void)setGoogleAPIKey:(NSString*)googleAPIKey
+               clientID:(NSString*)clientID
+           clientSecret:(NSString*)clientSecret;
+
 // |configuration| must not be null
 - (instancetype)initWithFrame:(CGRect)frame
                 configuration:(CWVWebViewConfiguration*)configuration