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 157ed90a02db5844d0c3e00e02864434d63738ae..da06b5577e33646e9c5e58261fb480d58fea16b3 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"
@@ -93,6 +94,21 @@ static NSString* gUserAgentProduct = nil;
   gUserAgentProduct = [product copy];
 }
 
++ (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];