Retry failed Google requests if the message says to (#120)

Check the returned error message for a particular string. This is
of course fragile, but there doesn't look to be a better way,
and hopefully this is a short term workaround until our thumbnail
serving becomes more reliable.

Bug: T332125

src/Engine/GoogleCloudVisionEngine.php

@@ -70,6 +70,18 @@ public function getResult(
 		$imageUrlOrData = $image->hasData() ? $image->getData() : $image->getUrl();
 		$response = $this->imageAnnotator->textDetection( $imageUrlOrData, [ 'imageContext' => $imageContext ] );
 
+		// Re-try with direct upload if the error returned is something similar to
+		// "The URL does not appear to be accessible by us. Please double check or download the content and pass it in."
+		// There doesn't seem to be a specific error code for this (it is usually 3, but that's also used for other
+		// things), so it seems like we have to check the actual message string.
+		if ( $response->getError()
+			&& stripos( $response->getError()->getMessage(), 'download the content and pass it in' ) !== false
+		) {
+			$image = $this->getImage( $imageUrl, $crop, self::DO_DOWNLOAD_IMAGE );
+			$response = $this->imageAnnotator->textDetection( $image->getData(), [ 'imageContext' => $imageContext ] );
+		}
+
+		// Other errors, report to the user.
 		if ( $response->getError() ) {
 			throw new OcrException( 'google-error', [ $response->getError()->getMessage() ] );
 		}