Add the basic code skeleton for system info event router

chrome/browser/extensions/api/system_info_storage/system_info_storage_apitest.cc

Index: chrome/browser/extensions/api/system_info_storage/system_info_storage_apitest.cc
diff --git a/chrome/browser/extensions/api/system_info_storage/system_info_storage_apitest.cc b/chrome/browser/extensions/api/system_info_storage/system_info_storage_apitest.cc
index 9d467065b64c6b7c75ad9e932199b5b5a417ae2d..12dca8182d45aa3288617c757daa680c281cb3f7 100644
--- a/chrome/browser/extensions/api/system_info_storage/system_info_storage_apitest.cc
+++ b/chrome/browser/extensions/api/system_info_storage/system_info_storage_apitest.cc
@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 #include "base/command_line.h"
 #include "base/message_loop.h"
+#include "base/timer.h"
 #include "chrome/browser/extensions/api/system_info_storage/storage_info_provider.h"
 #include "chrome/browser/extensions/extension_apitest.h"
 #include "chrome/common/chrome_switches.h"
@@ -12,9 +13,13 @@ namespace extensions {
 using api::experimental_system_info_storage::StorageInfo;
 using api::experimental_system_info_storage::StorageUnitInfo;
 
+const int kDefaultInterval = 200; // default interval is 200ms.
+const int kAvailableCapacityBase = 10000;
+const int kChangeStep = 10;
+
 class MockStorageInfoProvider : public StorageInfoProvider {
  public:
-  MockStorageInfoProvider() {}
+  MockStorageInfoProvider() : timer_(NULL) {}
   virtual ~MockStorageInfoProvider() {}
 
   virtual bool QueryInfo(StorageInfo* info) OVERRIDE {
@@ -30,10 +35,46 @@ class MockStorageInfoProvider : public StorageInfoProvider {
     return true;
   }
 
-  virtual bool QueryUnitInfo(const std::string& id,
+  virtual bool QueryUnitInfo(const FilePath::StringType& path,
                              StorageUnitInfo* info) OVERRIDE {
     return false;
   }
+
+  virtual bool PlatformStartWatching(Delegate* delegate) OVERRIDE{
+    if (is_watching_) return false;
+
+    delegate_ = delegate;
+    timer_ = new base::RepeatingTimer<MockStorageInfoProvider>();
+    // Start the timer to emulate storage.onChanged event.
+    timer_->Start(FROM_HERE,
+                  base::TimeDelta::FromMilliseconds(kDefaultInterval),
+                  this, &MockStorageInfoProvider::OnTimeoutEvent);
+
+    is_watching_ = true;
+    return true;
+  }
+
+  virtual bool PlatformStopWatching() OVERRIDE {
+    if (!is_watching_) return false;
+    is_watching_ = false;
+    timer_->Stop();
+    delete timer_;
+    timer_ = NULL;
+    return true;
+  }
+
+ private:
+  void OnTimeoutEvent() {
+    static int count = 0;
+    if (delegate_) {
+      delegate_->OnStorageDeviceAvailableCapacityChanged(
+          "/dev/sda1", kAvailableCapacityBase - kChangeStep*count);
+      count++;
+    }
+  }
+
+  // Use a repeating timer to emulate storage free space change event.
+  base::RepeatingTimer<MockStorageInfoProvider>* timer_;
 };
 
 class SystemInfoStorageApiTest: public ExtensionApiTest {