[WebView] Reword crash handler message.

The current crash handler prints a message on logcat of the form
"### WebView crash. Version ..." whenever a crash is detected in an
Android app which happens to have a WebView.
Due to the in-process nature of the WebView, the crash handler is
triggered regardless of the actual cause of the crash, which might be
totally unrelated with the WebView or the chromium codebase at all.
The current wording is misleading as it erroneously suggests that the
crash is always due to the WebView.

BUG=456485
TBR=torne@chromium.org

Review URL: https://codereview.chromium.org/903363003

Cr-Commit-Position: refs/heads/master@{#315210}

android_webview/common/aw_crash_handler.cc

@@ -71,7 +71,7 @@ void RegisterCrashHandler(const std::string& version) {
     return;
   }
 
-  g_crash_msg = "### WebView crash. " + version;
+  g_crash_msg = "### WebView " + version;
   g_crash_msg_ptr = g_crash_msg.c_str();
 
   // Fail if unable to store all the old handlers.