Reactivate ProtoChromePromptIPCTest with improved logging and fixed bug.

Bug: 969139
Change-Id: I26fe6a4d739797ca8b5498fd3f7c1d54b0867820
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1762484
Commit-Queue: Oliver Li <olivierli@chromium.org>
Reviewed-by: Joe Mason <joenotcharles@google.com>
Cr-Commit-Position: refs/heads/master@{#689489}

chrome/chrome_cleaner/ipc/proto_chrome_prompt_ipc.cc

@@ -138,7 +138,9 @@ void ProtoChromePromptIPC::RunPromptUserTask(
   *chrome_prompt_request.mutable_prompt_user() = prompt_user_message;
 
   std::string request_content;
-  DCHECK(chrome_prompt_request.SerializeToString(&request_content));
+  bool serialize_result =
+      chrome_prompt_request.SerializeToString(&request_content);
+  DCHECK(serialize_result);
 
   SendBuffer(request_content);
 
@@ -161,7 +163,8 @@ void ProtoChromePromptIPC::RunPromptUserTask(
   *chrome_prompt_request.mutable_close_connection() = close_connection_request;
 
   std::string response_content;
-  DCHECK(chrome_prompt_request.SerializeToString(&response_content));
+  serialize_result = chrome_prompt_request.SerializeToString(&response_content);
+  DCHECK(serialize_result);
 
   SendBuffer(response_content);
 

chrome/chrome_cleaner/ipc/proto_chrome_prompt_ipc.h

@@ -94,6 +94,7 @@ class ProtoChromePromptIPC : public ChromePromptIPC {
       OnConnectionError();
       return;
     }
+
     if (bytes_written != size) {
       LOG(ERROR) << "Incorrect number of bytes written to the pipe. Should be: "
                  << size << " but is :" << bytes_written;