Move the translate script callbacks from TranslateManager to TranslateScript

This CL refactors the way callbacks for TranslateScript are handled.
Previously, only one callback was allowed, and thus TranslateManager was
managing a global list of pending script request to be able to merge all these
requests into one callback.

As we want to move away from TranslateManager being a singleton, the management
of TranslateScript requests is moved to TranslateScript (which is also cleaner).
TranslateScript now supports multiple callbacks.

BUG=332736

Review URL: https://codereview.chromium.org/166553003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251666 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 19 insertions, 13 deletions

diff --git a/components/translate/core/browser/translate_script.cc b/components/translate/core/browser/translate_script.cc
index a83f499..68b5cff 100644
--- a/components/translate/core/browser/translate_script.cc
+++ b/components/translate/core/browser/translate_script.cc
@@ -51,14 +51,16 @@ TranslateScript::TranslateScript()
 TranslateScript::~TranslateScript() {
 }
 
-void TranslateScript::Request(const Callback& callback) {
+void TranslateScript::Request(const RequestCallback& callback) {
+  DCHECK(data_.empty()) << "Do not fetch the script if it is already fetched";
+  callback_list_.push_back(callback);
+
   if (fetcher_.get() != NULL) {
-    NOTREACHED();
+    // If there is already a request in progress, do nothing. |callback| will be
+    // run on completion.
     return;
   }
 
-  callback_ = callback;
-
   GURL translate_script_url;
   // Check if command-line contains an alternative URL for translate service.
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
@@ -145,5 +147,10 @@ void TranslateScript::OnScriptFetchComplete(
         expiration_delay_);
   }
 
-  callback_.Run(success, data);
+  for (RequestCallbackList::iterator it = callback_list_.begin();
+       it != callback_list_.end();
+       ++it) {
+    it->Run(success, data);
+  }
+  callback_list_.clear();
 }
diff --git a/components/translate/core/browser/translate_script.h b/components/translate/core/browser/translate_script.h
index 552daee..156d3a5 100644
--- a/components/translate/core/browser/translate_script.h
+++ b/components/translate/core/browser/translate_script.h
@@ -6,8 +6,9 @@
 #define COMPONENTS_TRANSLATE_CORE_BROWSER_TRANSLATE_SCRIPT_H_
 
 #include <string>
+#include <vector>
 
-#include "base/callback.h"
+#include "base/callback_forward.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
@@ -18,7 +19,7 @@ class TranslateURLFetcher;
 
 class TranslateScript {
  public:
-  typedef base::Callback<void(bool, const std::string&)> Callback;
+  typedef base::Callback<void(bool, const std::string&)> RequestCallback;
 
   static const int kFetcherId = 0;
 
@@ -40,10 +41,7 @@ class TranslateScript {
 
   // Fetches the JS translate script (the script that is injected in the page
   // to translate it).
-  void Request(const Callback& callback);
-
-  // Returns true if this has a pending request.
-  bool HasPendingRequest() const { return fetcher_.get() != NULL; }
+  void Request(const RequestCallback& callback);
 
  private:
   friend class TranslateScriptTest;
@@ -83,8 +81,9 @@ class TranslateScript {
   // server.
   base::TimeDelta expiration_delay_;
 
-  // The callback called when the server sends a response.
-  Callback callback_;
+  // The callbacks called when the server sends a response.
+  typedef std::vector<RequestCallback> RequestCallbackList;
+  RequestCallbackList callback_list_;
 
   base::WeakPtrFactory<TranslateScript> weak_method_factory_;