Reusing the base::StringPairs in src/components/*

Reusing the "base::StringPairs" insted of  "std::vector<std::pair<std::string, std::string> >"
same is defined in  base/strings/string_split.h.

BUG=412250

Review URL: https://codereview.chromium.org/593113002

Cr-Commit-Position: refs/heads/master@{#297387}

components/leveldb_proto/proto_database_impl.h

@@ -16,12 +16,13 @@
 #include "base/strings/string_util.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/threading/thread_checker.h"
+#include "base/strings/string_split.h"
 #include "components/leveldb_proto/leveldb_database.h"
 #include "components/leveldb_proto/proto_database.h"
 
 namespace leveldb_proto {
 
-typedef std::vector<std::pair<std::string, std::string> > KeyValueVector;
+typedef base::StringPairs KeyValueVector;
 typedef std::vector<std::string> KeyVector;
 
 // When the ProtoDatabaseImpl instance is deleted, in-progress asynchronous

components/policy/core/common/cloud/device_management_service.h

@@ -15,11 +15,13 @@
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
+#include "base/strings/string_split.h"
 #include "components/policy/core/common/cloud/cloud_policy_constants.h"
 #include "components/policy/policy_export.h"
 #include "net/url_request/url_fetcher_delegate.h"
 #include "policy/proto/device_management_backend.pb.h"
 
+
 namespace net {
 class URLRequestContextGetter;
 }
@@ -73,7 +75,7 @@ class POLICY_EXPORT DeviceManagementRequestJob {
   void Start(const Callback& callback);
 
  protected:
-  typedef std::vector<std::pair<std::string, std::string> > ParameterMap;
+  typedef base::StringPairs ParameterMap;
 
   DeviceManagementRequestJob(JobType type,
                              const std::string& agent_parameter,

components/policy/core/common/cloud/device_management_service_unittest.cc

@@ -359,7 +359,7 @@ class QueryParams {
   }
 
  private:
-  typedef std::vector<std::pair<std::string, std::string> > ParamMap;
+  typedef base::StringPairs ParamMap;
   ParamMap params_;
 };
 

components/search/search.h

@@ -11,6 +11,7 @@
 
 #include "base/basictypes.h"
 #include "base/strings/string16.h"
+#include "base/strings/string_split.h"
 
 namespace chrome {
 
@@ -23,7 +24,7 @@ bool IsInstantExtendedAPIEnabled();
 uint64 EmbeddedSearchPageVersion();
 
 // Type for a collection of experiment configuration parameters.
-typedef std::vector<std::pair<std::string, std::string> > FieldTrialFlags;
+typedef base::StringPairs FieldTrialFlags;
 
 // Finds the active field trial group name and parses out the configuration
 // flags. On success, |flags| will be filled with the field trial flags. |flags|