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

ios/web_view/internal/cwv_web_view.mm

Index: ios/web_view/internal/cwv_web_view.mm
diff --git a/ios/web_view/internal/cwv_web_view.mm b/ios/web_view/internal/cwv_web_view.mm
index 08fb4d8dc30b2994005f51fbd5799b2b1efbc42c..0da46bd48a7c6b8c517da960386e2403ce02aa41 100644
--- a/ios/web_view/internal/cwv_web_view.mm
+++ b/ios/web_view/internal/cwv_web_view.mm
@@ -10,6 +10,7 @@
 #import "base/ios/weak_nsobject.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/sys_string_conversions.h"
+#include "google_apis/google_api_keys.h"
 #import "ios/web/public/navigation_manager.h"
 #include "ios/web/public/referrer.h"
 #include "ios/web/public/reload_type.h"
@@ -60,6 +61,21 @@
 @synthesize estimatedProgress = _estimatedProgress;
 @synthesize UIDelegate = _UIDelegate;
 
++ (void)setGoogleAPIKey:(NSString*)googleAPIKey
+               clientID:(NSString*)clientID
+           clientSecret:(NSString*)clientSecret {
+  google_apis::SetAPIKey(base::SysNSStringToUTF8(googleAPIKey));
+
+  std::string clientIDString = base::SysNSStringToUTF8(clientID);
+  std::string clientSecretString = base::SysNSStringToUTF8(clientSecret);
+  for (size_t i = 0; i < google_apis::CLIENT_NUM_ITEMS; ++i) {
+    google_apis::OAuth2Client client =
+        static_cast<google_apis::OAuth2Client>(i);
+    google_apis::SetOAuth2ClientID(client, clientIDString);
+    google_apis::SetOAuth2ClientSecret(client, clientSecretString);
+  }
+}
+
 - (instancetype)initWithFrame:(CGRect)frame
                 configuration:(CWVWebViewConfiguration*)configuration {
   self = [super initWithFrame:frame];