Blimp: create MessageDispatcher class.

testing/buildbot/tryserver.chromium.linux.json

 {
   "android_chromium_gn_compile_dbg": {
     "additional_compile_targets": [
       "chrome_public_apk",
       "chrome_public_test_apk",
       "content_shell_apk",
       "mandoline:all"
     ]
   },
   "android_chromium_gn_compile_rel": {
@@ skipping 141 matching lines @@
       "ui_base_unittests",
       "ui_touch_selection_unittests",
       "unit_tests",
       "url_unittests",
       "views_unittests",
       "wm_unittests"
     ]
   },
   "linux_chromium_gn_rel": {
     "additional_compile_targets": [
+      "blimp",

[nyquist, 2015/09/10 21:56:48]

Could you add to linux_chromium_gn_dbg as well? (same for
blimp_common_unit_tests below)

[Kevin M, 2015/09/23 00:05:30]

Done.

       "browser_tests",
       "mandoline:all"
     ],
     "gtest_tests": [
       {
         "test": "accessibility_unittests"
       },
       {
         "test": "app_list_unittests"
       },
       {
         "test": "aura_unittests"
       },
       {
         "test": "base_unittests"
       },
       {
+        "test": "blimp_common_unit_tests"
+      },
+      {
         "test": "cacheinvalidation_unittests"
       },
       {
         "test": "cast_unittests"
       },
       {
         "test": "cc_unittests"
       },
       {
         "test": "chromedriver_unittests"
@@ skipping 164 matching lines @@
         "name": "gyp_flag_compare",
         "script": "gyp_flag_compare.py"
       },
       {
         "name": "mojo_apptests",
         "script": "mojo_apptests.py"
       }
     ]
   }
 }